Ashcroft 1259, 1279 Operating Manual
PRESSURE GAUGE
INSTALLATION,
OPERATION AND
MAINTENANCE
I&M008-10098-5/02 (250-1353-L) Rev. 12/15
1
2
CONTENTS
1.0 Selection and Application
1.1 Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.2 Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.3 Media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.4 Oxidizing media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.5 Pulsation/Vibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.6 Gauge fills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.7 Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.0 Temperature
2.1 Ambient Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.2 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.3 Steam service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.4 Hot or very cold media . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
2.5 Diaphragm seals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
2.6 Autoclaving . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.0 Installation
3.1 Installation Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.2 Gauge reuse . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.3 Tightening of gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.4 Process isolation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.5 Surface mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
3.6 Flush mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.0 Operation
4.1 Frequency of inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.2 In-service inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.3 When to check accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.4 When to recalibrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.5 Other considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
4.6 Spare parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
5.0 Gauge Replacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
6.0 Accuracy: Procedures/Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
6.1 Calibration - Rotary movement gauges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
7.0 Diaphragm Seals
7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
7.2 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
7.3 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
7.4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
7.5 Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.0 Dampening Devices
8.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.2 Throttle Screws & Plugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.3 Ashcroft Pulsation Dampener . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.4 Ashcroft Pressure Snubber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.5 Ashcroft Needle Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
8.6 Chemiquip
9.0 Test Equipment & Tool Kits
9.1 Pressure Instrument Testing Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
9.2 Tools & Tool Kits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
9.3 Kits to Convert a Dry Gauge to a Liquid Filled or . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Weather Proof Case Gauge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
9.4
Appendix
Type 1188 Bellows Gauge Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11
Type 1009 Calibration Procedure (Vacuum-Previous Style) . . . . . . . . . . . . . . . . . . . . . . . . . . .12
Type 1009 Calibration Procedure (Pressure-Previous Style) . . . . . . . . . . . . . . . . . . . . . . . . . .13
Type 1009 Calibration Procedure (Pressure & Vacuum-Current Style) . . . . . . . . . . . . . . . . . .14
Type 1279 & 1379 I&M Liquid Fill Conversion Instruction . . . . . . . . . . . . . . . . . . . . . . . . . .15-16
Type 1082 Calibration Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17-18
21⁄2 & 31⁄2 1009 Duralife®Gauge Tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10
®
Pressure Limiting Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Page
Cover photo courtesy of Johnson/Yokogawa Co.
Chemiquip®is a registered trademark of Chemiquip Products Co. Inc.
3
1.0 SELECTION & APPLICATION
sers should become familiar with ASME B40.100 (Gauges
U
– Pressure Indicating Dial Type – Elastic Element) before
specifying pressure measuring gauges. That document –
ontaining valuable information regarding gauge construction,
c
accuracy, safety, selection and testing – may be ordered from:
ASME International
Three Park Avenue
New York, N.Y. 10016-5990
800-843-2763 (US/Canada)
001-800-843-2763 (Mexico)
973-882-1170 outside North America
email: infocentral@asme.org
www.asme.org
WARNING:
should be selected considering media and ambient operating
conditions. Improper application can be detrimental to the
gauge, causing failure and possible personal injury, property
damage or death. The information contained in this manual is
offered as a guide in making the proper selection of a pressure
gauge. Additional information is available from Ashcroft Inc.
The following is a highlight of some of the more important considerations:
1.1 Range – The range of the instrument should be approximately twice the maximum operating pressure. Too low a
range may result in (a) low fatigue life of the elastic element
due to high operating stress and (b) susceptibility to overpressure set due to pressure transients that exceed the normal operating pressure. Too high a range may yield insufficient resolution for the application.
1.2 Temperature – Refer to Section 2 of this manual for
important information concerning temperature related limitations of pressure gauges, both dry and liquid filled.
1.3 Media – The material of the process sensing element must
be compatible with the process media. Use of a diaphragm seal
with the gauge is recommended for process media that (a) is
corrosive to the process sensing element; (b) contain heavy
particulates (slurries) or (c) are very viscous including those
that harden at room temperature.
1.4 Oxidizing media – Gauges for direct use on oxidizing
media should be specially cleaned. Gauges for oxygen service should be ordered to variation X6B and will carry the
ASME required dial marking “USE NO OIL” in red letters.
Gauges for direct use on other oxidizing media may be
ordered to variation X6W. They will be cleaned but carry no
dial marking. PLUS!
filled gauge or diaphragm fill is required for use with oxidizing media; order variation XCF.
1.5 Pulsation/Vibration – Pressure pulsation can be dampened by several mechanisms; the patented PLUS! Perfor-
mance gauge will handle the vast majority of applications.
One exception to this is high frequency pulsation which is
difficult to detect. The only indication may be an upscale zero
shift due to movement wear. These applications should be
addressed with a liquid filled gauge, or in extreme cases, a
remotely mounted liquid filled gauge connected with a length
of capillary line. The small diameter of the capillary provides
excellent dampening, but can be plugged. The Ashcroft 1106
pulsation dampener and 1112 snubber are auxiliary devices
which dampen pulsation with less tendency to plug.
1.6 Gauge fills. – Once it has been determined that a liquid
filled gauge is in order, the next step is selecting the type of fill.
To prevent misapplication, pressure gauges
™
Performance gauges or Halocarbon
Glycerin satisfies most applications. While being the least
xpensive fill, its usable temperature range is 20/180°F.
e
Silicone filled gauges have a broader service range: –
40/250°F. Oxidizing media require the use of Halocarbon,
ith a service range of –40/250°F. Pointer motion will be
w
slowed at the low end of the low end of these temperature
ranges.
1.7 Mounting – Users should predetermine how the gauge
will be mounted in service: stem (pipe), wall (surface) or panel
(flush). Ashcroft wall or panel mounting kits should be ordered
the gauge. See Section 3.
with
2.0 TEMPERATURE
2.1 Ambient Temperature – To ensure long life and accura-
cy, pressure gauges should preferably be used at an ambient temperature between –20 and +150°F (–30 to +65°C).
At very low temperatures, standard gauges may exhibit slow
pointer response. Above 150°F, the accuracy will be affected
by approximately 1.5% per 100°F. Other than discoloration of
the dial and hardening of the gasketing and degradation of
accuracy, non-liquid filled Type 1279 (phenolic case) and
1379 (aluminum case) Duragauge
glass windows, can withstand continuous operating temperatures up to 250°F. Unigauge models 2
1008S liquid filled gauges can withstand 200°F but glycerin
fill and the acrylic window of Duragauge
yellow. Silicone fill will have much less tendency to yellow.
Low pressure, liquid filled Types 1008 and 1009 gauges may
have some downscale errors caused by liquid fill expansion.
This can be alleviated by venting the gauge at the top plug
(pullout the blue plug insert). To do this the gauge must be
installed in the vertical position.
Although the gauge may be destroyed and calibration lost,
gauges can withstand short times at the following temperatures: gauges with all welded pressure boundary joints, 750°F
(400°C); gauges with silver brazed joints, 450°F (232°C) and
gauges with soft soldered joints, 250°F (121°C). For expected
long term service below –20°F (–30°C) Duragauge
1009 gauges should be hermetically sealed and specially
lubricated; add “H” to the product code for hermetic sealing.
Add variation XVY for special lubricant. Standard Duralife
gauges may be used to –50°F (–45°C) without modification.
2.2 Accuracy – Heat and cold affect accuracy of indication.
A general rule of thumb for dry gauges is 0.5% of full scale
change for every 40°F change from 75°F. Double that al lowance for gauges with hermetically sealed or liquid filled
cases, except for Duragauge
allowance is required due to the elastomeric, compensating
back. Above 250°F there may exist very significant errors in
indication.
2.3 Steam service – In order to prevent live steam from
entering the Bourdon tube, a siphon filled with water should
be installed between the gauge and the process line.
Siphons can be supplied with ratings up to 4,000 psi. If
freezing of the condensate in the loop of the siphon is a possibility, a diaphragm seal should be used to isolate the
gauge from the process steam. Siphons should also be used
whenever condensing, hot vapors (not just steam) are present. Super heated steam should have enough piping or
capillary line ahead of the siphon to maintain liquid water in
the siphon loop.
2.4 Hot or very cold media – A five foot capillary line assembly will bring most hot or cold process media within the recommended gauge ambient temperature range. For media above
®
gauge, with standard
1
⁄2˝ and 31⁄2˝ 1009 and
®
gauges will tend to
®
gauges where no extra
®
and 41⁄
2˝
®
4
750°F (400°C) the customers should use their own small
diameter piping to avoid possible corrosion of the stainless steel.
he five foot capillary will protect the gauges used on the com-
T
mon cryogenic (less than –300°F (200°C) gases, liquid argon,
nitrogen, and oxygen.) The capillary and gauge must be
cleaned for oxygen service. The media must not be corrosive to
stainless steel, and must not plug the small bore of the capillary.
2.5 Diaphragm seals – A diaphragm seal should be used to
protect gauges from corrosive media, or media that will plug
the instrument. Diaphragm seals are offered in a wide variety
of designs and corrosion resistant materials to accommodate almost any application and most connections. Visit
www.ashcroft.com for details.
.6 Autoclaving – Sanitary gauges with clamp type connec-
2
tions are frequently steam sterilized in an autoclave. Gauges
equipped with polysulfone windows will withstand more autoclave cycles than those equipped with polycarbonate windows. Gauges equipped with plain glass or laminated safety
glass should not be autoclaved. Gauge cases should be
vented to atmosphere (removing the rubber fill/safety plug if
necessary) before autoclaving to prevent the plastic window
from cracking or excessively distorting. If the gauge is liquid
filled, the fill should be drained from the case and the front
ring loosened before autoclaving.
3.0 INSTALLATION
3.1 Location – Whenever possible, gauges should be located to minimize the effects of vibration, extreme ambient temperatures and moisture. Dry locations away from very high
thermal sources (ovens, boilers etc.) are preferred. If the
mechanical vibration level is extreme, the gauge should be
remotely located (usually on a wall) and connected to the
pressure source via flexible tubing.
3.2 Gauge reuse – ASME B40.100 recommends that
gauges not be moved indiscriminately
to another. The cumulative number of pressure cycles on an
in-service or previously used gauge is generally unknown, so
it is generally safer to install a new gauge whenever and
wherever possible. This will also minimize the possibility of a
reaction with previous media
3.3 Tightening of gauge – Torque should never be applied
to the gauge case. Instead, an open end or adjustable
wrench should always be used on the wrench flats of the
gauge socket to tighten the gauge into the fitting or pipe.
NPT threads require the use of a suitable thread sealant,
such as pipe dope or teflon tape, and must be tightened very
securely to ensure a leak tight seal.
.
CAUTION: Torque applied to a diaphragm seal or its
attached gauge, that tends to loosen one relative to the
other, can cause loss of fill and subsequent inaccurate readings. Always apply torque only to the wrench flats on the
lower seal housing when installing filled, diaphragm seal
assemblies or removing same from process lines.
3.4 Process isolation – A shut-off valve should be installed
between the gauge and the process in order to be able to
isolate the gauge for inspection or replacement without shutting down the process.
3.5 Surface mounting – Also known as wall mounting.
Gauges should be kept free of piping strains. The gauge case
mounting feet, if applicable, will ensure clearance between the
pressure relieving back and the mounting surface.
3.6 Flush mounting – Also known as panel mounting. The
applicable panel mounting cutout dimensions can be found
at www.ashcroft.com
from one application
4.0 OPERATION
4.1 Frequency of inspection – This is quite subjective and
depends upon the severity of the service and how critical the
accuracy of the indicated pressure is. For example, a monthly inspection frequency may be in order for critical, severe
service applications. Annual inspections, or even less frequent schedules, are often employed in non-critical applications.
.2 In-service inspection – If the accuracy of the gauge
4
cannot be checked in place, the user can at least look for (a)
erratic or random pointer motion; (b) readings that are sus-
ect – especially indications of pressure when the user
p
believes the true pressure is 0 psig. Any gauge which is
obviously not working or indicating erroneously, should be
mmediately valved-off or removed from service to avoid a
i
possible pressure boundary failure.
4.3 When to check accuracy – Any suspicious behavior of
the gauge pointer warrants that a full accuracy check be performed. Even if the gauge is not showing any symptoms of
abnormal performance, the user may want to establish a frequency of bench type inspection.
4.4 When to recalibrate – This depends on the criticality of
the application. If the accuracy of a 3-2-3% commercial type
gauge is only 0.5% beyond specification, the user must
decide whether it’s worth the time and expense to bring the
gauge back into specification. Conversely if the accuracy of
a 0.25% test gauge is found to be 0.1% out of specification
then the gauge should be recalibrated.
4.5 Other considerations – These include (a) bent or unattached pointers due to extreme pressure pulsation; (b) broken windows which should be replaced to keep dirt out of
the internals; (c) leakage of gauge fill; (d) case damage –
dents and/or cracks; (e) any signs of service media leakage
through the gauge including its connection; (f) discoloration
of gauge fill that impedes readability.
4.6 Spare parts – As a general rule it is recommended
that the user maintain in inventory one complete Ashcroft
instrument for every ten (or fraction thereof) of that
instrument type in service.
®
5.0 GAUGE REPLACEMENT
It is recommended that the user stock one complete
Ashcroft
instrument type in service. With regard to gauges having a
service history, consideration should be given to discarding
rather than repairing them. Gauges in this category include
the following:
a. Gauges that exhibit a span shift greater than 10%. It is
b. Gauges that exhibit a zero shift greater than 25%. It is
c. Gauges which have accumulated over 1,000,000 pres-
d. Gauges showing any signs of corrosion and/or leakage
e. Gauges which have been exposed to high temperature
®
instrument for every ten (or fraction thereof) of that
possible the Bourdon tube has suffered thinning of its
walls by corrosion.
likely the Bourdon tube has seen significant overpressure leaving residual stresses that may be detrimental
to the application.
sure cycles with significant pointer excursion.
of the pressure system.
or exhibit signs of having been exposed to high temperature – specifically 250°F or greater for soft soldered
systems; 450°F or greater for brazed systems; and
750°F or greater for welded systems.
5
f. Gauges showing significant friction error and/or wear of
he movement and linkage.
t
g. Gauges having damaged sockets, especially damaged
threads.
h. Liquid filled gauges showing loss of case fill.
NOTE: ASME B40.100 does not recommend moving gauges
rom one application to another. This policy is prudent in that
f
it encourages the user to procure a new gauge, properly tailored by specification, to each application that arises
.
6.0 ACCURACY: PROCEDURES/DEFINITIONS
Accuracy inspection – Readings at approximately five
oints equally spaced over the dial should be taken, both
p
upscale and downscale, before and after lightly rapping the
gauge to remove friction. A pressure standard with accuracy
at least four times greater than the accuracy of the gauge
being tested is recommended.
Equipment – A finely regulated pressure supply will be required.
It is critical that the piping system associated with the test setup
be leaktight. The gauge under test should be positioned as it will
be in service to eliminate positional errors due to gravity.
Method – ASME B40.100 recommends that known pres-
ure (based on the reading from the pressure standard used)
s
be applied to the gauge under test. Readings including any
error from the nominal input pressure, are then taken from the
auge under test. The practice of aligning the pointer of the
g
gauge under test with a dial graduation and then reading the
error from the master gauge (“reverse reading”) can result in
nconsistent and misleading data and should NOT be used.
i
Calibration chart – After recording all of the readings it is
necessary to calculate the errors associated with each test
point using the following formula: ERROR in percent = 100
times (TRUE VALUE minus READING) ÷ RANGE. Plotting
the individual errors (Figure 1) makes it possible to visualize
the total gauge characteristic. The plot should contain all four
curves: upscale – before rap; upscale – after rap; downscale
– before rap; downscale – after rap. “Rap” means lightly tapping the gauge before reading to remove friction as
described in ASME B40.100.
Referring to Figure 1, several classes of error may be seen:
Zero – An error which is approximately equal over the entire
scale. This error can be manifested when either the gauge is
FIG. 1
TYPICAL CALIBRATION CHART
INDICATED VALUE (PSI)
True Value – Increasing – Increasing – Decreasing – Decreasing –
PSI Without RAP With RAP Without RAP With RAP
0 –.4 0 –.4 0
40 +.8 +1.0 +1.4 +1.1
80 +.4 +.5 +1.2 +1.0
120 –.4 –1.0 +.8 +.6
160 –.8 –.5 +.6 +.4
200 +.4 +.8 +.4 +.4
ERROR (% OF FULL SCALE)
True Value – Increasing – Increasing – Decreasing – Decreasing –
% of Range Without RAP With RAP Without RAP With RAP
0 –.20 0 –.20 0
20 +.40 +.50 +.70 +.55
40 +.20 +.25 +.60 +.50
60 –.20 –.05 +.40 +.30
80 –.40 –.25 +.30 +.20
100 +.20 +.40 +.20 +.20
1.0
◆
◆
■
◆
●
▲
■
◆
■
●
▲
0.5
■
●
▲
●
0.0
▲
Error (% of Full Scale)
–0.5
–1.0
▲ ▲ upscale – without rap
● ● upscale – with rap
◆ ◆ downscale – without rap
■ ■ downscale – with rap
0 20 40 60 80 100
% of Range
●
▲
6
●
▲
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