Ashcroft Model A4A
Precision Pressure Gauge
Installation and
Maintenance Manual
1
I&M002-10126-02/14
2
INDEX
Section Description
1.0 Scope
1.1 Safety Precautions
2.0 Product Description
2.1 Theory of Operation
2.2 Pressure Types
2.3 Gauge Construction
3.0 Incoming Inspection
3.1 Unpacking
3.2 Installation
4.0 Initial Operation
4.1 Bleeding The System
4.2 Zero, Tare or Barometric Setting
4.3 General Operating Considerations
5.0 Calibration
5.1 Calibration Standards
5.2 Calibration Check
5.3 Recalibration Procedure
6.0 Pointer Replacemen
t
6.1 Guide to Pointer Replacement
7.0 Specifications
7.1 Standard Specifications
8.0 Warranty & Shipping Instructions
8.1 Warranty & Limitation of Liability
8.2 Shipping Instructions
9.0 To Order An A4A Gauge
9.1 Information Necessary to Specify an A4A Gauge
APPENDICES
Appendix A- Standard Graduation Table
Appendix B- Standard Range Selection
Appendix C- Gauge Dimensions
1.0 PURPOSE AND SCOPE OF MANUAL
This manual is prov
ided by Ashcroft Inc. to guide users of
the Ashcroft Model A4A precision pressure gauge in:
(1) Installation
(2) Routine operations
The instructions in this manual are designed to be per-
formed by qualified instrument maintenance personnel.
Ashcroft Inc. does not recommend trouble-shooting or
repairs beyond the scope of this manual. Problems which
cannot be remedied by following the instructions in this
ual should be referred to the manufacturer.
man
For Additional Assistance
Contact Customer Service at:
Ashcroft Inc.
250 East Main Street
Stratford, CT 06614
Phone: (203) 378-8281
Fax: (203) 385-0402
1.1 SAFETY PRECAUTIONS
Bourdon tube pressure gauges must be selected and used
in accordance with recognized industry codes and safety
practices. This is necessary in order to avoid the possibility
of misuse or misapplication which could result in personal
or property damage. Personnel responsible for selec-
injury
tion and installation should also be familiar with the safety
recommendations of ASME B40.1 that apply to elastic
pressure elements and their application in general and specific services. ASME B40.1 is available from:
ASME
345 47th Street
New York, NY 10017
The primary considerations in gauge selection are:
1. Pressure
Select a range so that the maximu
m applied pressure will never exceed the upper range limit.
ASME B40.1 recommends gauges be selected so
that normal operation will occur between 25-75%
of the full scale range of the gauge.
2. Vibration
Excessive vibration could cause loosening of components resulting in loss of instrument accuracy or
failure to provide valid data. Remote mounting can
often protect a gauge from damage due to vibration.
. Pulsation
3
Excessive pressure pulsation could result in fatigue
failure of the pressure element. Commercially available pressure snubbers can be used to protect a
gauge from damage due to pressure pulsation.
4. Temperature
Operation of the instrument in an environmentwhere temperatures are in excess of design ratings may result in loss of accuracy and failure.
Optional temperature compensation is reco
mmended for gauges to be used in areas that are
not temperaturecontrolled.
5. Process
Pressure boundary materials (Bourdon tube and
socket) must be resistant to the processmedia.
Failure to assure compatibility between the pressure media and boundary materials may result in
pressure sensing element deterioration or failure.
Instrumentsused on high pressure gas or in potentially hazardous service, such
as oxygen, should
becarefully selected in accordance with the recommendations of ASME B40.1.
See also Section 3.2
3
Ashcroft A4A Dial Gauge
2.0 PRODUCT DESCRIPTION – THEORY OF
OPERATION - CONSTRUCTION
The Ashcroft A4A is a mechanical pressure gauge. This is a
device that measures pressure via the movement of an elastic element which is subjected to the pressure to be measured. This element is “powered” only by the pressure itself. It
requires no external power source to perform its function.
2.1 THEORY OF OPERATION
The Ashcroft A4A precision
pressure gauge consists of a
Bourdon tube elastic element, a movement, case, dial and
pointer. The accuracy of a pressure gauge is contingent on
the performance capabilities of the sensing element, movement and the accuracy of the scale graduations which are
imprinted on the dial.
A mechanical pressure gauge measures pressure by converting the movement of the elastic element into the move-
ment of a
pointer across a dial.
The Ashcroft A4A precision pressure gauge incorporates a
highly engineered Bourdon tube as a pressure sensing element. A Bourdon tube is a piece of tubing that has been
bent into a circular shape. Depending on the pressure
range the Ashcroft A4A gauge may include a single or
multi-coil Bourdon tube.
During the measurement process pressure is introduced to
the inside of the Bourdon
tube via the externally accessible
process connection. When pressure is applied to the Bourdon tube it straightens out a small amount (vacuum actually
pulls the free end of the coil in tighter). Since the process
connection is locked into position by the mounting of the
Bourdon tube into the gauge case, the movement caused
by the application of pressure or vacuum is limited to the
loose end or the tip
of the tube. This tube movement is
commonly called deflection or tip travel.
The tip travel is converted to a pressure measurement via a
system of gears that drive a pointer. The gear system is
commonly referred to as the gauge movement.
The pointer moves with the application of pressure or vacuum over a dial imprinted with information including pressure
range, engineering units, graduations and other pertinent
information.
The main differences between an Ashcroft A4A gauge and
other “precision pressure gauges” can be found in the
Bourdon tube and the quality of the other components used
in the gauge. The process of making a Bourdon tube for the
A4A gauge takes 15 days to complete and produces the
most highly developed pressure sensing element of its
. In the A4A gauge this tube is combined with a move-
type
ment which incorporates precision brass gears and miniature stainless steel ball bearings to provide the most accurate conversion of tip travel to pointer movement possible.
These components are all mounted in a heavy duty cast
aluminum case which provides a rigid base. As a result of
the rigid mounting platform the A4A is immune to inaccura-
aused by pipe strain and case flexing. In many other
cy c
gauges these are common problems often caused by
stresses generated during the installation process.
2.2 TYPES OF ASHCROFT A4A PRECISION
PRESSURE GAUGES
The Ashcroft A4A is available in four standard dial sizes, 6”
8-1/2”, 12” and 16”and pressure ranges from 15 through
100,000 psi. Dials are provided with the required divisions to
meet specification and
may be graduated to read in standard
English or metric units of pressure. Special dials in other
pressure related engineering units or with dual scales to
eliminate need for conversion, are available upon application.
The Ashcroft A4A is available to measure gauge, absolute
and compound pressures as well as vacuum. Since the
absolute A4A gauge does not have a hard vacuum reference it must be set to th
e prevailing barometric pressure by
the operator. A brief description of the available pressure
types follows:
Gauge Pressure
Measures and indicates pressure
using ambient pressure as a reference point. Provides the pressure measurement as a differential between the pressure input
and the prevailing barometric
pressure.
Vacuum Gauge
Measures and indicates pressure
below ambient, using ambient
pressure as
the reference point.
All readings taken with a vacuum
gauge are negative. The largest
vacuum level achievable at any
given time is the negative equivalent of the prevailing barometric
pressure at the start of the test
cycle.
4
EXTERNAL “ZERO”
ADJUSTMENT
BEZEL
WINDOW
GASKET
POINTER
WINDOW
DIAL CASE
PRESSURE
RELIEF
DISC
MOVEMENT
BOURDON
TUBE
PRESSURE
ELEMENT
Compound Gauge
Measures and indicates pressure
above and below ambient pressure, using ambient pressure as a
reference point. A compound
gauge is a combination of a
gauge pressure and a vacuum
pressure gauge.
Absolute Pressure Gauge
Measures and indicates pressure
above zero absolute pressure,
using absolute zero pressure as a
reference point. All measurements made with an absolute
pressure gauge will be po
sitive as
it is impossible to generate a
pressure below that of zero
absolute pressure.
NOTES:
1. Ambient pressure equals pressure surrounding the mea-
suring element, generally atmospheric pressure.
2. The Ashcroft A4A absolute pressure gauge does not
incorporate automatic barometric pressure compensation.
The barometric pressure at the time of use must be set by
using the External Dial Adjuster.
Optional Fea
tures
Where specified, gauges have been equipped with automatic thermal compensator, slotted link for protection
against sudden pressure release, peak load indicating
pointers or other optional features. See Section 2.3.5 for
Complete Details on Available Options.
2.3 CONSTRUCTION
2.3.1 CASE AND BEZEL
Solid Front Case
A solid front case of cast aluminum protects the operator
when working with high pressure systems. In the event of
tube rupture through excessive over pressure, protection is
provided by this wall as pressure release will be directed out
the back of the gauge, away from the operator
Blow-Out Safety Back
A light gauge stainless steel disc, covering the entire back
of the gauge case, is spring-loaded against a seal
machined in the periphery of the case. An abnorm
al rise of
pressure within the gauge case causes this disc to flex outward, releasing the pressure.
Bezel
A hinged bezel protecting the dial and pointer is equipped
with an external dial zero adjustment. It is also the mounting
for the lens.
External dial Zero Adjustment
A zero adjustment knob on the front of the gauge case
makes it possible to set dial zero to atmospheric pressure
or other benchmarks req
uired.
Limit Stops
High and low pressure limit stops are mounted on the interior of the gauge case, restraining tube tip travel within the
rated operating range of the gauge. The limit stops protect
the movement from becoming disengaged due to excessive
tip travel. They do not protect the Bourdon tube from damage to over-pressure.
2.3.2 BOURDON TUBE SYSTEM
The Ashcroft A4A Bourdon tube is a product of m
ore than
40 years of intensive, continuous research. The “unitized”
one-piece tube system is an outstanding example of modern technology.
Through exclusive Ashcroft A4A Bourdon tube designs and
manufacturing techniques, uniform stress distribution is provided in a wide range of tubes of varying cross sectional
configurations. All A4A tubes are formed from a single piece
of seamless tube material.
of 403 stainless steel are standard for ranges of 50
Tubes
psi and above. Beryllium Copper may be supplied for low
5
Ashcroft A4A multi-coiled
Bourdon tube
pressures and special applications. See Section 7.1 for
additional information.
The Bourdon tube used in the Ashcroft A4A Gauge is a
“Unitized” single or multi-coil element which is approximately three times the length of tubes used in competitive
gauges. The greater length results in a much lower deflection rate, minimizes stress and virtually eliminates hystere
-
sis, creep and fatigue effect.
The unitized tube design eliminates soldered, welded or
threaded joints which further provides for controlled distribution of stress during the tube forming operations. Internal
traps in which foreign matter may accumulate are also eliminated. The interior of the Ashcroft A4A tube may be easily
cleaned by positive flow through flushing through the stan-
dard tip flushi
ng (bleeder cap) connector.
Heat Treatment
All Ashcroft A4A Bourdon tubes are heat treated in high
vacuum to maintain internal cleanliness and optimize
mechanical properties.
Ultra-High Pressure Gauges
Ashcroft laboratories pioneered and continues to lead in the
development of precision Bourdon tubes for ultra-high pressure gauges in ranges to 100,000 psi.
External Bleeder Cap
In order to achieve optimal
accuracy the Bourdon tube
should be bled prior to initiating operation. If the gauge is to
be used on a gaseous media oil trapped in the Bourdon
tube should be purged from the tube. If the gauge is to be
used in liquid service trapped gas should be removed from
the Bourdon tube. Both activities are facilitated by the bleeder cap (flushing connector) which is an integral part of the
Bourdon tube. The bl
eeder cap is accessed by removing
the blow out disc from the back of the gauge.
Pressure Connection
Pressure connections may be either bottom or back locations. A complete listing of the available connections is provided in the specifications section (7.0) of this manual.
Tip Piece Assembly
The tip piece assembly is pivotally mounted on the free end
of the Bourdon tube. It comprises a quadrant and cla
mp
arrangement to permit adjustment of its angular position,
and a quadrant slide upon which the connecting link is pivoted. It is used to establish the angular relationship of the
connecting link and the sector slide which controls linearity
in the pointer movement.
Connecting Link
The Connecting Link transmits motion from the tip piece
assembly to the sector slide of the movement.
2.3.3 MOVEMENT ASSEMBL
Y
Integral Movement
The solid front case provides a single rigid support for all
moving parts of the gauge, maintaining critical alignment
under all conditions. No significant calibration error will
occur in the Ashcroft A4A gauge, as a result of distortion or
shifting of supporting parts or components during the installation process.
Miniature Stainless Steel Ball Bearings
Friction and wear are minimize
d and sensitivity improved at
the pinion shaft by precision miniature stainless steel ball
bearings. Smooth action at this critical point in the movement assures an immediate, accurate response to minute
pressure changes. This makes the Ashcroft A4A gauge the
most sensitive instrument of its type.
Gear Sector and Drive
The gear sector drives the pointer pinion directly in the
Ashcroft Model A4A precisio
n pressure gauge. The pointer
pinion is spring loaded against backlash by a hair spring.
For maximum accuracy it is important that the original tooth
relationship be maintained throughout the system. If, for any
reason, the gears are to be disengaged they should first be
marked to assure correct re-engagement.
Hair Spring
The hair spring takes up backlash in the gearing and maintains the smooth sensitiv
e action of the movement. This
spring has been pre-set to approximately 2 turns counter
clockwise with zero pressure applied. Lack of hair spring
tension will result in erratic pointer motion. Should this
occur, the gears may be disengaged, observing the precautions noted above, the hair spring tightened, and the gears
re-engaged.
Sector Slide (course span adjustment)
The sector slide is mounted on the
gear sector. It permits
adjustment of the ratio of pointer travel to Bourdon tube
motion by altering the multiplication through the “MicroSlide” adjustment. This adjustment controls the pointer travel or range of the gauge (see figure 5.2).
Micro Slide Adjustment (fine span adjustment)
The micro slide adjustment provides convenient and simplified development in calibration methods. When required,
ecise recalibration adjustment may be made in the total
pr
effective length of the sector slide. The micrometer screw
attached to the slide may be adjusted to 0.0005” when
extremely minute corrections are necessary. The pre-loaded
adjustment spring stabilizes the calibration setting against
accidental shock (see figure 5.2).
6
Tip Piece Adjustment
The unique quadrant and slide design of the Ashcroft A4A
adjustable tip piece permits simple and accurate adjustment
of the angular relationship between the connecting link and
sector slide. This adjustment controls linearity; coupled with
the range adjustment it may be used to readily recalibrate
the gauge (see figure 5.2).
Thermal Compensator (optional)
Holds the gauge in calibrati
on to the ±0.1% accuracy rating
through ambient temperature ranges from -25ºF to +125ºF.
2.3.4 DIAL AND POINTER
Concentric Dial Mounting
The dial is supported at the center by a dial pivot which
passes through the solid front gauge case and extends into
an aligning recess in the base casting of the movement.
This provides concentricity of the dial and pointer shaft of
the movement, assuring maximum accurac
y.
Dial
Black dial graduations on a white background are clearly
defined and highly legible assuring the resolution necessary
to obtain accurate measurements. All dials are generated
on a state of the art computer based design system. All
Ashcroft gauges include a mirror band which allows for the
elimination of parallax reading errors.
Each gauge carries an individual serial number on the dial
to facilitat
e identification.
For standard dial graduations see Graduation Tables
(Appendix A).
Pointer
The reading end of the knife-edge pointer provides a plane
which is perpendicular to the mirror band on the dial face
aiding in the elimination of parallax errors.
External Dial Zero Adjustment
A zero adjustment knob on the front of the gauge case
allows for easy zeroing of the gauge. This same adjustment
system allo
ws an operator to set the gauge to display barometric pressure, when setting up an absolute A4A gauge or
to set the dial to some other predetermined pressure preload. One knob rotates the dial, not the pointer, through
approximately 30 degrees of arc; the other knob locks the
bezel. A friction brake, acting on the dial, prevents acciden-
tal rotation.
Where a constant value is to be carried through a
series of
readings, such as a tare*, this adjustment eliminates the
need for computing values at each reading.
*A tare value is a pressure pre-load which may not need to
be reflected in the measured value. For example, in weighing operations the pressure generated by the weighing platform is often tared or zeroed out prior to beginning the mea-
surement process.
2.3.5 OPTIONAL FEATURES
Special Scales
e Ashcroft A4A gauge may be ordered with special
Th
scales to indicate pressure or pressure equivalent units in
any scale desired. Commonly used scales include standard
English (psi, inches of water, etc), metric (kg/cm2, bar, mm
Hg, etc) or SI (Pascal) units, feet of water (fresh-sea), force
on ram, absolute, vacuum, compound (vacuum-pressure) or
dual scale.
Special Ranges
The Ashcroft A4A precision pressur
e gauge is available in a
wide variety of standard pressure ranges from 15 through
100,000 psi. A list of the standard ranges is provided in
Appendix B. Most any non-standard pressure range
between 15 and 100,000 psi or metric equivalent can be
provided on a custom basis.
Thermal Compensator (Patented)
The thermal compensator is comprised of a bimetallic bar
which forms part of the linkage between the tip
of the Bourdon tube and the gear segment slide of the gauge movement. Deflection of the bimetallic bar, resulting from a
change in ambient temperature, causes the point at which
motion is imparted to the gear segment slide, to move in an
arc. This results in a change in both the angular position
and effective length of the slide. The length of the bimetallic
bar is trimmed specifically to offset the
thermal characteris-
tics of the Bourdon tube with which it is used.
Correction for ambient temperature change is completely
automatic and requires no adjustment of the compensator,
pointer or dial for any temperature variation from -25ºF to
+125ºF.
Important Note: The bimetallic bar is matched to the specific Bourdon tube for which it has been configured. The
bimetallic link cannot be removed for use i
n another gauge.
In addition, any damage to a temperature compensated
gauge that results in the need to replace the Bourdon tube
will also necessitate the replacement of the thermal compensation option. This can only be accomplished at the factory.
Slotted Link
The slotted link option is designed to protect gauges from
movement damage which could result in applications that
produce sudden, violent relea
se of system pressure. When
gauges are used for burst or tensile testing, comprehensive
strength testing or similar applications, a sudden release of
pressure is the norm. In these types of applications a slotted link prevents violent flutter of the pointer and possible
damage to the gauge movement.
Peak Load Indicator
It is often necessary to retain the highest or lowest measured value during a press
ure cycle or test. The peak load
indicator is available to simplify the recording of this information. The peak load indicator is a red tracking pointer,
often referred to as a lazy hand. Movement of the pointer
actuates the peak load indicator in either a positive or negative direction. The red pointer will remain at the highest or
lowest measured value during the pressure cycle. An exterior knob
permits convenient resetting for subsequent pressure cycles. The peak load indicator has been carefully
engineered so that it will not diminish the ±0.1% accuracy of
the A4A gauge.
Carrying Case
Sturdy, impact resistant, black grain finish carrying cases,
with protective insert, for carrying any size Ashcroft A4A
bottom connected gauge are available.
3.0 INCOMING INSPECTION
3.1 UNPACKING GAUGE
Every Ashcrof
t A4A gauge is carefully packaged to prevent
shipping damage.
After unpacking, visually inspect the gauge for any damage
that may have occurred during shipment.
7
If damage is observed consult factory for further instructions.
Ashcroft A4A gauges are shipped with a small piece of
plastic sponge between the pointer hub and the inside of
the glass. This prevents the pointer from “whipping” during
shipment. When your new gauge is unpacked, this cushion
should be removed and discarded.
To remove this cushion first remove the inner small chrome
knob at the bottom of t
he bezel by unscrewing it in a counterclockwise direction. Next lift the bottom of the bezel and
slide it off the upper hinge pin.
Note: When replacing the bezel gently turn the outer dial
adjustment knob (large chrome knob) to assure that the
gear teeth on the adjuster mesh with the rack on the dial.
All Ashcroft A4A gauges are accurately calibrated to ±0.1%
of full scale or better, against standards
that are traceable to
the National Institute of Standards of Technology. A certified
copy of test results is furnished with each gauge. Standard
conditions for calibration conform to NIST Monograph 8.
To check gauge accuracy after unpacking, follow instructions in Section 5.0 – Calibration.
Important Information
Gauges for use with corrosive or hazardous media such as
mercury or radioactive solutions sh
ould be tested with a
non-corrosive non-hazardous medium such as air, water or
oil prior to acceptance. Faults found after an instrument has
been contaminated will be the sole responsibility of the user.
Contaminated instruments may not be returned to the factory without written authorization. Failure to obtain authoriza-
tion may inadvertently result in injury to Ashcroft Inc. personnel and/or prope
rty damage. Contaminated gauges
returned without prior written approval will be returned to
the sender unrepaired.
3.2 INSTALLATION
*** WARNING ***
Where the gauge is to be used with oxygen, it should be
clearly specified and the gauge will be so marked either on
the dial for 8
1
⁄2, 12 and 16 inch gauges or on the back of the
gauge for the 6 inch dial size. In these cases, special precautions are taken to eliminate all traces of organic matter
which might otherwise cause an explosion hazard.
The gauge should not be used with elements or compounds deleterious to the wetted materials.
Gauges are factory calibrated in an upright or vertical position, unless otherwise specified on the order. Gauges
should always be mounted in the same position as calibrat-
ed to eliminate possibility of positional error.
If gauges are to
be mounted in other than vertical position the order should
specify the angle in which to be mounted to permit factory
calibration in the same position.
Mounting dimensions are given in the dimensional drawings
and charts in Appendix C.
4.0 OPERATION
All Ashcroft A4A pressure gauges are precision instruments
and certain precautions must be observed in their operation.
4.1 BLEEDING THE SYSTEM
The gauge should be mounted in an upright position when
connected to a liquid pressure system and the bleeder
(flushing connector) should be operated before readings are
taken. Accurate readings on a liquid pressure system are
impossible unless all air or other gas has been evacuated.
All Ashcroft A4A gauges are equipped with a bleeder valve
(flushing connector) as an integral part of the Bourdon tube.
hen operating the bleeder valve (flushing connector) sup-
W
port the free end of the Bourdon tube with fingers to prevent
disengagement of the gear teeth or possible bending of the
link or tip piece. To operate the bleeder, the valve is opened
slightly and pressure applied to the gauge to force fluid
through the tube and out the valve. To avoid getting fluid in
the movement assembly it is recommended that
a tube or
some type of shield be used to direct the liquid flow away
from the gauge case and movement. Since some oil may
have accumulated near the bleeder valve tube after factory
calibration, the fluid should be permitted to flow for several
seconds. Any air or gas present in the gauge should then
escape followed by a steady flow of the pressure medium.
The bleeder may then be closed.
It is good proced
ure to apply full pressure on the gauge for
several minutes before each period of use. The pressure
should then be removed and the dial zero adjusted, if necessary.
4.2 SETTING DIAL TO ZERO OR TARE OR VALUE
All Ashcroft A4A gauges are equipped with a dial adjuster
and friction brake. The dial adjuster is operated from the
front cover of the case and moves the dial – not the pointer
– through approximatel
y 30 degrees of rotation. This adjustment is used to set zero, tare out a pressure pre-load or,
with absolute gauges to set the pointer to the prevailing
barometric pressure. In tests involving an initial pressure
which is ordinarily carried through the calculations as a tare,
resetting of the dial will simplify the calculations by eliminating the tare figure entirely.
4.2.1 SETTING DIAL TO PREVAILING
BAROMETRIC
PRESSURE (ABSOLUTE GAUGES ONLY)
The dial adjuster is also used to allow an A4A gauge to simulate the performance of an absolute pressure gauge. To do
this the gauge operator must determine the prevailing barometric pressure from an accepted source (such as an inhouse barometer or a nearly airport). Once this is known
the operator, using the dial adjuster, rotates the dial so that
e gauge connection vented to atmosphere the point-
with th
er is directed to the prevailing barometric. Once this is
accomplished, the external adjustment locking nut should
be tightened. With the pointer set to barometric pressure
prior to connecting the process connection to the pressure
input the gauge will measure pressure in terms of absolute
pressure. Periodically, to adjust for changing barometric
pressur
e, the process connection of the gauge must be
vented to atmosphere and the dial adjusted to display the
prevailing barometric pressure.
4.3 GENERAL OPERATING CONSIDERATIONS
The Ashcroft A4A gauge is “Test” or “Master” gauge and if
properly cared for should retain its inherent accuracy indefinitely. However, where gauges are used for highly critical
work over a long period of time, it is good practice t
o check
them at regular intervals against a deadweight tester. The
procedure for testing and adjusting is given in Section 5.0.
Pressure Surges
Utmost precaution must be taken at all times to protect the
gauge from high pressure surges or shocks. The sudden
application or removal of pressure will cause the pointer to
whip around and, by its inertia, to damage the movement,
or may move the pointer on its s
8
haft. This effect can be min-
imized or eliminated through the use of commercially available pressure snubbers.
When the application for which the gauge is to be used
involves the sudden release of pressure, the “Slotted Link”
option should be specified at the time of order to protect the
movement assembly.
Temperature Error
Ashcroft A4A gauges are typically used where tempera-
tures are maintained within close limits. In cases whe
re
extreme temperature variations will be encountered, corrections may be calculated and applied to the gauge readings.
When temperatures rise the Bourdon tube reads faster and
when they drop it reads slower at a rate of one percent per
50ºF. In these cases, the automatic bimetallic thermal compensation option is recommended for greater accuracy and
convenience. When equipped with the bimetallic comp
ensator, the gauge accuracy will be maintained through temperature from -25ºF to +125ºF.
Loose Pointer
Gauge error may be caused by a loose pointer. If pointer
shift is suspected, simply release pressure and check that
the pointer returns to the zero position. If an adjustment is
necessary first position the zero adjust mechanism in the
middle of its full range of adjustability. Once this is accom-
shed, move the pointer to the proper position and, using
pli
your fingers, press it firmly onto the shaft. The pointer
should never be hammered or tapped in place.
5.0 CALIBRATION
5.1 CALIBRATION STANDARDS
In order to properly check and adjust the calibration of a
precision gauge, a reliable standard of reference is
required. Care should be taken in the selection of a dead-
weight tester since the resulting ope
ration of the precision
dial gauge can be no more accurate than the standard on
which it is based.
A primary pressure standard with accuracy of ±0.025 percent of reading or better is recommended to properly check
or calibrate the Ashcroft A4A. Corrections for local gravity
effects, air buoyancy and temperature should be applied to
the pressure standard to compensate for environmental
conditions.
Note: If
a secondary transfer standard is used, it should be
of the same range as the instrument being tested and have
accuracy of ±0.025 percent of span or better.
If you would prefer, NIST traceable recalibration of your
Ashcroft A4A Precision Pressure Gauge can be performed
at the Ashcroft Inc., Stratford, CT facility. Priority Recertification can be arranged to assure the gauge is calibrated and
shipped for
return to your facility within 5 days of receipt at
the Stratford Operation. Contact Ashcroft Inc. Customer and
Support Service at (203) 378-8281 for further details on
available calibration services.
5.2 CALIBRATION CHECK
Apply full pressure on the gauge for several minutes and
then release the pressure. Re-zero the gauge, if necessary.
Using an appropriate pressure standard generate pressures
and take r
eadings at zero to full scale in 10% increments,
both upscale and downscale. If the error exceeds the
amount permissible for the intended service, follow the
recalibration procedure (Section 5.3).
5.3 RECALIBRATION PROCEDURE
Prior to beginning calibration on a fluid media the Bourdon
tube must be completely free of entrapped gas or, if calibration is to be done on a gas system, the Bourdon tube must
ree of any liquid.
be f
5.3.1 Linearity Test
Step 1-
Load the gauge to full scale pressure and return to zero.
Step 2-
Adjust the pointer to zero with the dial centered. If necessary, remove pointer then center the zero adjust mechanism
and replace pointer.
Step 3-
Load the gauge to one-half scale pressure and record the
reading.
Step 4-
Load the gauge to full scale pressure and record the reading. If linearity
is normal, the reading at full scale pressure
should be double the reading at one-half scale pressure so
as to produce a straight line relationship.
If the readings are not linear, recalibration procedure as follows is indicated:
5.3.2 Linearity Adjustment
Step 1-
First the gauge must be “straight lined”. That is to make the
readings linear or proportional to the load. At this point the
actual value of th
e readings at any given load is secondary.
Once linearity has been established, range adjustment to
bring the full scale reading into agreement with the full scale
load will complete the calibration.
Unscrew the zero adjust locking knob and remove the two
knobs and then remove the bezel and window by lifting the
bottom up and away from the gauge face.
Step 2-
Remove the back blow out cover by unscrewing t
he knurled
knob on the center back of the gauge and lifting away the
stainless steel blow out disc.
CAUTION:
Prior to proceeding it is recommended that the tooth relationship between the sector and its mating pinion be
marked (see figure 5.1). If the sector and pinion are accidentally disengaged these marks will assist in proper reengagement. For optimum performance the original tooth
engagement shou
ld be maintained.
Step 3-
To compensate for a full scale reading greater than twice
the one-half scale reading:
Consult Figures 5.1 & 5.2
Loosen the two clamping screws on the quadrant slide and
slide it upward, thereby decreasing the angle. Or, if the error
is slight, rotate the pointer and pinion shaft counter clockwise to indicate about twice the extent of the error. Holding
the pointer in this positi
on, release the quadrant clamp
screw permitting the Bourdon tube to adjust its position,
then re-clamp. This also results in a decrease in angle.
To compensate for a full scale reading less than twice the
one-half scale reading use the same procedure outlined in
step 3 except as follows:
9
Figure 5.1
Model “A4A”
10
Figure 5.2
11
Consult Figures 5.1 & 5.2
Move the quadrant slide outward, thereby increasing the
angle, or rotate the pointer and pinion shaft clockwise to
indicate about twice the amount of the error. Holding the
pointer in this position release the quadrant clamp screw
permitting the Bourdon tube to adjust its position, then reclamp. This also results in an increase in angle.
Step 4-
Reset the pointer to zero and
repeat the linearity check to
evaluate the adjustment. Repeat procedure until linearity is
established within the desired tolerance.
5.3.3 Range Test
Step 1-
Load the gauge to full scale pressure by dead weight and
note the reading on the gauge. If the full scale reading is not
correct within the required tolerance proceed as follows:
Step 2-
If the pointer indicates greater pressure than the dead
weight, tu
rn the Micro-Slide adjusting screw counter-clockwise. If the pointer indicates less pressure than the dead
weight, turn the Micro-Slide adjusting screw clockwise.
Should the range adjustment be excessive, loosen the two
Micro-Slide clamping screws and move the slide inward to
increase the range and outward to decrease the range.
Adjustment of the Micro-Slide screw changes the amount of
pointer travel b
etween zero and full scale. It is necessary
after each adjustment to return the pressure to zero, readjust the pointer to zero and repeat to determine the effectiveness of the adjustment.
Adjustment of the Micro-Slide screw requires a movement
of approximately 180 degrees in order to have a pointer
show a change of ? of one percent of full scale reading on
most gauge dials. To correct some gauges an
adjustment of
as little as 0.0005” or a turn of approximately 10º of the
Micro-Slide screw is required. The adjusting screw may be
operated with a small Allen wrench.
5.3.4 Final Adjustment
The range and linearity adjustments are interdependent.
With linearity established, fine readjustment may be made
in range and linearity re-checked to bring both adjustments
within the desired limits of accuracy.
5.3.5 Ch
eck For Hysteresis
Step 1-
Connect the gauge to the deadweight tester in a vertical
operating position.
Step 2-
If the gauge has been drained, fully or partially, air may be
entrapped in the Bourdon tube and this trapped air must be
removed through the bleeder valve (flushing connector) to
insure positive, accurate response.
If the gauge has been used with and contains mercury, care
should be taken to avoid
contamination of brass tubing and
fittings on the tester.
Gauges used in pneumatic systems should, of course, be
cleaned of oil, water or similar entrapped matter before testing.
Step 3-
Set the pointer to zero using the dial adjustment.
Step 4-
Applying pressure slowly, load the gauge to one-half scale
pressure and record the reading.
Step 5-
Load to full scale pressure.
Step 6-
Release to one-half scale pr
essure and compare the down-
scale reading to the upscale reading.
If the second reading is higher than the first it may be
caused by either hysteresis or friction. With dead weight still
at one-half load, tap the gauge gently. If the pointer returns
to substantially the original one-half load reading, the difference in readings was caused by friction. If the amount of tap
is not excessive it might be
considered satisfactory for use.
It is normal procedure to tap an instrument to observe its
sensitivity. If the tap is excessive it is usually remedied by
cleaning the movement mechanism with solvent such as
ether, carbon tetrachloride, etc.
If after tapping the gauge the pointer still reads higher than
the first reading, the cause is hysteresis. Increased hysteresis effect may be brought about by crys
tallization of the
Bourdon tube due to excessive cycling. A similar condition
may result from exposure to excessively high pressure
causing a partial fracture of the tube. In cases where the
Bourdon tube has been found to have unacceptable levels
of hysteresis a new tube is required. It is recommended that
gauges requiring a new Bourdon tube be returned to the
factory for repair.
Note: If a new Bourdon tu
be is required for a gauge that has
the optional bimetallic thermal compensation a new thermal
compensation will be required.
6.0 POINTER REPLACEMENT
6.1 GUIDE TO POINTER REPLACEMENT
A “perfect” gauge can be defined as a gauge which yields a
reading which is exactly equal to the actual pressure which
is being applied. Plotted on a graph, these points can be
connected to form a straight line, indicating perf
ect “linearity”. If a point was plotted that did not fall along this line, it
can be said that this is a “non-linear” reading. Most pressure
instruments exhibit some inherent non-linearity characteristics, due mainly to a disproportionate movement of the
sensing element (Bourdon tube) under different pressures.
Prior to correction, an Ashcroft A4A precision pressure
gauge will generally, in the firs
t half of the scale, indicate a
higher pressure reading than the actual applied pressure
(called “running fast”), and will be the fastest at ? scale. The
gauge will usually read perfectly at midpoint, run “slow” in
the second half of the scale (slowest at ? scale) and read
perfectly at full scale.
In order to maintain high accuracy, some form of compensation must be employed to overcome the additional
racy caused by non-linearity. There are two methods of
compensation for non-linearity in Ashcroft A4A gauges:
1-Non-Linear Dials
These gauges are manufactured with balanced pointers
and dials on which the graduations have been plotted to
coincide with the position of the pointer at specific pressure
points. The placement of the graduations is determined by
the use of readings recorded during the p
reliminary calibration of each gauge. These readings will then be programmed into a computer linked to a photo-plotter, which
will produce a negative image of the dial. A positive dial is
then produced from this negative.
12
inaccu-
If the gauge is adjusted considerably or if movement parts
are replaced, it will probably be impossible to re-use the
existing dial, and a new dial will have to be plotted as part of
the calibration.
2-Counter-Weighted Pointer
With this method, we begin by producing a “linear” dial. (A
dial upon which the graduations are evenly spaced). Next,
we take a “balanced” pointer and remove the half moon at
end of the tail. By removing the half moon, the pointer is
the
no longer balanced because the tail end is now lighter than
the indicating (knife edge) end. This will cause the heavy
pointer tip to “sag” or read “slow” in the first half of the scale
and read “fast” in the second half of the scale, actually overcompensating for the original non linearity condition.
To achieve the required effect, which is t
o flatten out the S
curve, a counterweight is added to the tail end of the pointer
to add back some of the weight that was lost when the half
moon was removed.
By adding a counterweight, also called a “poise” onto the
tail-end of the pointer gravity can be used to force the tail of
the pointer “downward”, which conversely deflects the tip of
the pointer “upward”. In the first half of the scale, the counterweight will cause the gauge to read faster. In the second
half of the scale, the counterweight will cause the gauge to
read slower. Since the gauge was reading slow in the first
half of the scale, the faster readings caused by the counterweight will compensate for the non-linearity. Conversely, the
second half of the scale which was reading fast, will be
slowed by the counterweight.
In fact, because
of the gravitational effect is decreased as
the pointer approaches a vertical position (due to the
decreased moment of inertia), the counterweight will cause
no effect on the pointer at mid-scale, which is always plotted
in the 12 o’clock position on the dial. This is ideal, as no
compensation is necessary at mid-scale. The counterweight
will cause the greatest effect at ? scale (9:00) and ? scale
), which is where the most compensation is required.
(3:00
Properly set, the amount of compensation caused by the
counterweight will exactly offset the amount of inherent nonlinearity as shown by the “S” curve.
Notes:
1-It is important to note that the counterweight can only be
effective when the gauge is used in the vertical or near vertical operating position. Gauges used in the horizontal posi-
always require non-linear dials.
tion will
2-Gauges with 6” dials do not have pointers with half moon
tails. Instead, the tail end of the pointer is wider than the
indicating end. The counterbalance offset is accomplished
by trimming the tail end of the pointer until the desired counterbalance effect is achieved.
The following general rules can be used to help determine
whether a gauge has a linear or non-linea
r dial.
Ashcroft A4A Gauges with Non-Linear Dials
-All vacuum and compound gauges
-All absolute gauges 75 psi or less
-All gauges calibrated in the horizontal position
-Some dual scale gauges
-All gauges originally equipped with “crescent moon”
pointer tail tips
Ashcroft A4A Gauges with Linear Dials
-All that are other than above
-All gauges originally equipped with counter weighted pointers
Note: When perfo
rming linearization via pointer trimming it
is important that the trimming be done carefully so as not to
remove too much material which would result in the need to
discard the pointer and start the process over.
7.0 SPECIFICATIONS, RANGES & DIMENSIONS
7.1 STANDARD SPECIFICATIONS
Unless otherwise specified all gauges are calibrated for vertical mounting. If installation is other than vertical, the order
ust specify mounting positions to assure proper accuracy.
m
A certified copy of test results, traceable to the National
Institute of Standards and Technology, is furnished with
each gauge. Standard conditions for calibration conform to
NIST Monograph 8.
Accuracy ±0.1% of span
Sensitivity ±0.01% of span
Repeatability ±0.02% of full scale
Hysteresis Not greater than ±0.1% of span after
application of maximum scale
pressure
Pressure Types Gauge, compound, absolute* and vacuum
Pressure Ranges From 0-15 psi through 0-100,000 psi
Bourdon Tube
Material Bourdon tubes are available in the
following materials:
STANDARD
Beryllium Copper for ranges from 0-15
through 0-40 psi AISI 403 stainless steel
standard for range 0-50 psi through
0-100,000 psi
OPTIONAL
Beryllium Copper for ranges from 0-50
through 0-10,000 psi. AISI 403 sta
inless
steel for ranges 0-15 psi through 0-40 psi
Standard Process
Connections
1
⁄4 NPT female back for ranges to 10,000
psi. 9/16-18 UNF-2B female back connections for ? inch high pressure tubing for
ranges over 10,000 psi
Optional Process
Connections
1
⁄4 NPT female, bottom
1
⁄8 NPT male, back or bottom
1
⁄4 NPT male, back or bottom
1
⁄8 NPT female, back or bottom
9
⁄16-18 UNF-2B female, bottom or back or
bottom for ranges below 10,000 psi
MS 33656-4 male, back or bottom
Mil-G-18997D male, back or bottom
MS 33649-4 female, back or bottom
MS 16142 female, back or bottom
13
*The Ashcroft A4A Absolute Pressure Gauge does not
incorporate Automatic barometric pressure compensation.
The barometric pressure at the time of use must be set into
the gauge by using the External Dial Adjuster.
8.0 WARRANTY AND SHIPPING INSTRUCTIONS
8.1 WARRANTY AND LIMITATION OF LIABILITY
All Ashcroft A4A products and parts carry a warranty
against defective material and workmanship for a period of
e (1) year from the date of shipment.
on
A complete warranty and limitation of liability statement is
provided on the standard Ashcroft A4A quotation form.
Copies of this form are provided with quotations and are
available upon request.
8.2 SHIPPING INSTRUCTIONS FOR RETURN
TO THE FACTORY
Pack securely to prevent possible damage in shipment. If
possible, using original packaging provided with the A4A
from Ashc
roft Inc.
Ship Package To:
Ashcroft Inc.
250 East Main Street
Stratford, CT 06614, USA
Attention: Heise Service Center
IMPORTANT – Obtain written authorization in order to
return instruments that have been used with or in contact
with corrosive or otherwise hazardous materials such as
mercury, radioactive solutions or toxic chemicals.
Please furnish the following information with the returned
instrument:
any Name
Comp
Phone Number
Person to Contact
Address
Model
Serial Number
Symptoms
9.0 TO ORDER A GAUGE
9.1 NECESSARY INFORMATION TO ORDER AN
ASHCROFT A4A PRECISION PRESSURE GAUGE
Please specify the following Gauge Attributes:
1. Model A4A
2. Dial Size (6”, 8?”, 12” and 16”)
3. Pressure Range
4. Confirm Bourdon tube material
5. Pressure Type (gauge, vacuum, compound or absolute)
6. Process Connection, type, gender & location
7.
Options desired
14
APPENDIX A STANDARD GRADUATION TABLES
Scale
for All
Units of
Measure
0-1
0-1.6
0-2
0-2.5
0-3
0-4
0-5
0-6
0-7.5
0-10
0-15
0-16
0-20
0-25
0-30
0-40
0-50
0-60
0-75
0-100
0-150
0-160
0-200
0-250
0-300
0-400
0-500
0-600
0-750
0-760
0-1000
0-1500
0-1600
0-2000
0-2500
0-3000
0-4000
0-5000
0-6000
0-7500
0-10000
0-15000
0-20000
0-25000
0-30000
0-40000
0-50000
0-60000
0-75000
0-100000
6˝ A4A & 81⁄
Total
fNumber Value
of per Division Numeral
Divisions Division Pattern Value
2˝ A4A 12˝ A4A 16˝ A4A
500 .002 1/5 .05
800 .002 1/5 .1
400 .005 1/2 .1
500 .005 1/2 .1
600 .005 1/2 .2
400 .01 1/5 .2
500 .01 1/5 .2
600 .01 1/5 .2
750 .01 1/5 .5
500 .02 1/5 .5
750 .02 1/5 1
800 .02 1/5 1
400 .05 1/2 1
500 .05 1/2 1
600 .05
4
00 .1 1/5 2
1/2 2
500 .1 1/5 2
600 .1 1/5 2
750 .1 1/5 5
500 .2 1/5 5
750 .2 1/5 10
800 .2 1/5 10
400 .5 1/2 10
500 .5 1/2 10
600 .5 1/2 20
400 1 1/5 20
500 1 1/5 25
600 1 1/5 25
750 1 1/5 50
760 1 1/5 40
500 2 1/5 50
750 2 1/5 100
800 2 1/5 100
400 5 1/2 100
500 5 1/2 100
600 5 1/2 200
400 10 1/5 200
500 10 1/5 250
600 10 1/5 250
750 10 1/5 500
500 20 1/5 500
750 20 1/5 1000
400 50 1/2 1000
500 50 1/2 1000
600 50 1/2 2000
400 100 1/5 2000
500 100 1/5 2500
600 100 1/5 2500
750 100 1/5 5000
500 200 1/5 5000
Total
fNumber Value
of per Division N
Divisions Division Pattern Value
umeral
1000 .001 1/5 .05
800 .002 1/5 .1
1000 .002 1/5 .1
1000 .0025 1/4 .1
600 .005 1/2 .2
800 .005 1/2 .2
1000 .005 1/2 .2
600 .01 1/5 .2
750 .01 1/5 .5
1000 .01 1/5 .5
750 .02 1/5 1
800 .02 1/5 1
1000 .02 1/5 1
1000 .025 1/4 1
600 .05 1/2 2
800 .05 1/2 2
1000 .05 1/2 2
600 .1 1/5 2
750 .1 1/5 5
1000 .1 1/5 5
750 .2 1/5 10
800 .2 1/5 10
1000 .2 1/5 10
1000 .25 1/4 10
600 .5 1/2 20
800 .5 1/2 20
1000 .5 1/2 20
600 1 1/5 25
750 1 1/5 50
760 1 1/5 40
1000 1 1/5 50
750 2 1/5 100
800 2 1/5 100
00
1000 2 1
/5 1
1000 2.5 1/4 100
600 5 1/2 200
800 5 1/2 200
1000 5 1/2 200
600 10 1/5 250
750 10 1/5 500
1000 10 1/5 500
750 20 1/5 1000
1000 20 1/5 1000
1000 25 1/4 1000
600 50 1/2 2000
800 50 1/2 2000
1000 50 1/2 2000
600 100 1/5 2500
750 100 1/5 5000
1000 100 1/5 5000
Total
fNumber Value
of per Division Numeral
Divisions Division Pattern Value
1000 .001 1/5 .05
800 .002 1/5 .1
1000 .002 1/5 .1
1250 .002 1/5 .1
1500 .002 1/5 .1
800 .005 1/2 .2
1000 .005 1/2 .2
1200 .005 1/2 .2
1500 .005 1/2 .5
1000 .01 1/5 .5
/5 .
1500 .01 1
5
800 .02 1/5 1
1000 .02 1/5 1
1250 .02 1/5 1
1500 .02 1/5 1
800 .05 1/2 2
1000 .05 1/2 2
1200 .05 1/2 2
1500 .05 1/2 5
1000 .1 1/5 5
1500 .1 1/5 5
800 .2 1/5 10
1000 .2 1/5 10
1250 .2 1/5 10
1500 .2 1/5 10
800 .5 1/2 20
1000 .5 1/2 20
1200 .5 1/2 20
1500 .5 1/2 50
1520 .5 1/2 40
1000 1 1/5 50
1500 1 1/5 50
800 2 1/5 100
1000 2 1/5 100
1250 2 1/5 100
1500 2 1/5 150
800 5 1/2 200
1000 5 1/2 200
1200 5 1/2 200
1500 5 1/2 500
1000 10 1/5 500
1500 10 1/5 500
1000 20 1/5 1000
1250 20 1/5 1000
1500 20 1/5 1000
800 50 1/2 2000
1000 50 1/2 200
200 50 1/2 2000
1
1500 50 1/2 5000
1000 100 1/5 5000
Scale
for All
Units of
Measure
0-1
0-1.6
0-2
0-2.5
0-3
0-4
0-5
0-6
0-7.5
0-10
0-15
0-16
0-20
0-25
0-30
0-40
0-50
0-60
0-75
0-100
0-150
0
0-16
-200
0
0-250
0-300
0-400
0-500
0-600
0-750
0-760
0-1000
0-1500
0-1600
0-2000
0-2500
0-3000
0-4000
0-5000
0-6000
0-7500
0-10000
0-15000
0-20000
0-25000
0-30000
0-40000
0
0-50000
0-60000
0-75000
0-100000
15
APPENDIX B STANDARD RANGE SELECTION
PSIG
STANDARD
BOURDON TUBE STANDARD RANGE PSIG CC CM CMM
MATERIAL**
0-12/3-15
0-15
BERYLLIUM
COPPER
(J)
403
STAINLESS
STEEL
(V)
0-20
0-25
0-30
0-40
0-50
0-60
0-75
0-100
0-150
0-200
0-250
0-300
0-400
0-500
0-600
0-750
0-1000
0-1500
0-2000
0-3000
0-4000
0-5000
0-6000
0-7500
0-10,000
0-15,000
0-20,000
0-25,000
0-30,000
0-40,000
0-50,000
0-60,000*
0-75,000*
0-100,000*
Inches Mercury
STANDARD
BOURDON TUBE
MATERIAL**
BERYLLIUM
COPPER
(J)
AISI 403
STAIN. STEEL
(V)
STANDARD RANGE
INCHES MERCURY
0-30
0-40
0-50
0-60
0-75
0-100
0-125
0-150
0-200
0-250
0-300
0-400
0-500
0-600
0-750
0-1000
Vacuum
BERYLLIUM
COPPER (J)
–30 to 0
Compound
VAC-PRESSURE CC CM CMM
BERYLLIUM
COPPER (J)
AISI 403
15˝ Hg - 15˝ Hg
30˝ Hg - 30˝ Hg
30˝ Hg - 60˝ Hg
STAIN. STEEL 30˝ Hg - 100˝ Hg
(V)
BERYLLIUM
COPPER (J)
30˝ Hg - 150˝ Hg
30˝ Hg - 15 psi
30˝ Hg - 30 psi
30˝ Hg - 60 psi
AISI 403
ST. STEEL
(V)
30˝ Hg - 100 psi
30˝ Hg - 150 psi
30˝ Hg - 300 psi
Inches Water
STANDARD
BOURDON TUBE
MATERIAL**
BERYLLIUM
COPPER
(J) 0-600
16
STANDARD RANGE
INCHES MERCURY
0-350
0-400
0-450
0-500
0-750
0-800
0-1000
CC CM CMM
CC CM CMM
APPENDIX B STANDARD METRIC RANGES
Metric
STANDARD
BOURDON TUBE
MATERIAL**
BERYLLIUM
COPPER
(J)
AISI 403
STAIN. STEEL
(V)
BERYLLIUM
COPPER
(J)
AISI 403
STAINLESS
STEEL
(V)
STANDARD RANGE
MILLIMETERS MERCURY
0-760
0-1000
0-1250
0-1500
0-2500
0-3000
0-4000
0-5000
bar
2
2
kPa mPa
kg/cm
kp/cm
0.2-1 ––
0-1 0-100 –
0-1.6 0-160 –
0-2 0-200 –
0-2.5 0-250 –
0-3 0-300 –
0-4 0-400 –
0-5 0-500 –
0-6 0-600 –
0-7.5 0-750 –
0-10 0-1000 0-1
0-12 0-1250 0-1.25
0-16 0-1600 0-1.6
0-20 0-2000 0-2
0-25 0-2500 0-2.5
0-30 0-3000 0-3
0-40 0-4000 0-4
0-50 0-5000 0-5
0-60 0-6000 0-6
0-75 0-7500 0-7.5
0-100 0-10,000 0-10
0-125 – 0-12.5
0-160 – 0-16
0-200 – 0-20
0-250 – 0-25
0-400 – 0-40
0-500 – 0-50
0-600 – 0-60
0-750 – 0-75
0-1000 – 0-100
0-1250 – 0-125
0-1600 – 0-160
0-2500 – 0-250
0-4000 –* 0-400
0-6000 –* 0-600
0-7000 –* 0-700
CC CM CMM
Vacuum
BERYLLIUM
COPPER
(J)
–1 to 0 –100 to 0
17
APPENDIX C GAUGE CASE DIMENSIONS
Model A4A
Dim.
Size ABCDEE1 E2 F
Units
⁄
8 8
3
⁄
4 12
3
⁄
4 16
Male –1⁄
1
⁄
2 7 21
15
1
⁄
16 9
⁄
2 21
3
1
⁄
8 9
⁄
2 21
3
1
⁄
8 9
⁄
2 21
8 Male NPT
1
⁄
4 Male NPT
MS 33656-4
in. 77⁄
6˝
mm 200 177.8 165.1 177.8 50.8 47.6 31.8 117.5 109.5 82.3 34.9 27 98.4 15.9 62.7
81⁄
in. 105⁄
2˝
mm 261.9 238.1 228.6 241.3 50.8 47.6 31.8 145.3 137.3 82.3 34.9 27 98.4 15.9 62.7
in. 1321⁄
12˝
mm 346.9 329.9 314.3 241.3 50.8 47.6 31.8 145.3 137.3 82.3 34.9 27 98.4 15.9 62.7
in. 1723⁄
16˝
mm 450.1 425.5 415.9 241.3 50.8 47.6 31.8 145.3 137.3 82.3 34.9 27 98.4 15.9 62.7
Inlet Pressure
Connection*
8 76
3
16 9
32 12
32 16
P
Dial Size 6˝ 81⁄
Weight
Net Weight 43⁄
Shipping Weight 61⁄
*Standard Inlet Fittings: 1⁄
4 NPT Female Back Connection for ranges up to and including 10,000 psi.
AMINCO 45-11310 or AUTOCLAVE F-250-C for ranges over 10,000 psi.
7
⁄
8 1
7
⁄
8 1
7
⁄
8 1
7
⁄
8 1
Female –1⁄
4 lbs. 6
4 lbs. 8
8 Female NPT
1
⁄
4 Female NPT
1
⁄
4 4
1
⁄
4 5
1
⁄
4 5
1
⁄
4 5
1
⁄
2 lbs. 9
1
⁄
2 lbs. 15 lbs. 18
18
M
5
23
23
23
2˝ 12˝ 16˝
F
F
5
⁄
8 4
⁄
16 3
13
⁄
32 5
⁄
32 3
13
⁄
32 5
⁄
32 3
13
⁄
32 5
⁄
32 3
AND 10050-4
Aminco 45-11310
Autoclave F-250-C
1
⁄
4 lbs. 12
GHMH
1
3
⁄
4 1
⁄
8 1
1
3
⁄
4 1
⁄
8 1
1
3
⁄
4 1
⁄
8 1
1
3
⁄
4 1
⁄
8 1
1
⁄
1
⁄
4 lbs.
4 lbs.
F
1
⁄
16 3
1
⁄
16 3
1
⁄
16 3
1
⁄
16 3
JKL
7
⁄
8
7
⁄
8
7
⁄
8
7
⁄
8
5
⁄
8 2
5
⁄
8 2
5
⁄
8 2
5
⁄
8 2
15
⁄
32
15
⁄
32
15
⁄
32
15
⁄
32
19
Ashcroft Inc. Sales and Customer Service Locations
World Headquarters
U.S.A.
Ashcroft Inc.250 East Main Street
Stratford, CT 06614-5145 U.S.A.
Tel: (203) 378-8281
Fax: (203) 385-0408 (Domestic)
Fax: (203) 385-0357 (Internat
ional)
email: heise@ashcroft.com
www.ashcroft.com
Visit our web site www.heise.com
All specifications are subject to change without notice.
All sales subject to standard terms and conditions.
©Ashcroft Inc. I&M002-10126 8/05 Rev. 02/14
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