Omega Products DWT1305DA-2000 Installation Manual

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DWT1305D Series

Deadweight Tester

DWT1327D

Portable Pressure Test Set

Operator’s Manual

Deadweight Tester

Rev 1.1 9/02

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An OMEGA Technologies Company

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1.0 PURPOSE AND SCOPE OF MANUAL

This manual is provided to guide users of Model
DWT1305D and DWT1327D pressure testing devices in:
(1) installing the equipment
(2) Routine operations

The instructions in this manual are designed to be per­formed by qualified instrument maintenance personnel.

Omega Engineering does not recommend troubleshooting
or repairs beyond the scope of this manual. Problems that
cannot be remedied by following the instructions in this
manual should be referred to Omega. Immediate assis­tance can often be supplied by telephone. Defective com­ponents will be repaired or replaced as necessary.
Returned goods should be accompanied by information
requested in Section 6.

1.1 Safety Precautions

Pressure Testing Equipment must be selected and used in
accordance with recognized industry codes and safety
practices to avoid the possibility of misuse or misapplica­tion which could result in personal injury or property dam­age. Personnel responsible for selection 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.

1. Pressure – Select a range so that the maximum
applied pressure will never exceed the upper range limit.

2. Vibration – Excessive vibration could cause a loosen­ing of components and abnormal wear resulting in loss of
instrument accuracy or failure to provide valid data.

3. Temperature – Operation of the instrument in an envi­ronment where temperatures are in excess of design rat­ings may result in loss of accuracy and failure.

4. Process – Pressure boundary materials must be resis­tant to the process media. Failure to assure compatibility
may result in pressure boundary deterioration or failure.
Instruments operated at high pressure or with potentially
hazardous service, such as oxygen, should be carefully
selected in accordance with recognized industry codes
and the recommendations of ASME B40.1.

2.0 PRODUCT DESCRIPTION –
THEORY OF OPERATION – CONSTRUCTION

2.1.2 Product Description

2.1.3 Construction

The Omega Type DWT1305D Dual Range Deadweight
testers are precision built primary pressure standards,
used for testing, setting, calibrating or repairing pressure
measuring devices within the test points 15 psi (100kPa)
to 10,000 psi (70,000kPa).

The deadweight tester consists of a two stage hydraulic
pump containing a manifold which is pressurized during
operation. Integral to the pump is a shuttle valve that
allows the operator to regulate the speed of pressure
increase. One connection to the manifold includes a cylin­der and a free-floating precision machined piston with a
plate for holding calibrated weights. A second connection
to the manifold accommodates a gauge or other pressure
measuring device to be calibrated or checked.
Incorporated into the manifold is a hand operated dis­placement valve that allows small adjustments in fluid vol­ume to be made without further operation of the pump
handle or release valve.

The tester is dual range having two interchangeable piston

Omega

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Installation and Maintenance Manual

for the Omega

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Type DWT1305D Deadweight Tester

and Type DWT1327D Portable Pump

INDEX
Section Description

1.

Scope of Manual Safety Precautions

2. Product Description DWT1305
Theory of Operation
Construction
Specifications

Product Description DWT1327
Theory of Operation
Construction
Specifications

3. Inspection
Installation DWT1305
Operation DWT1305
Installation DWT1327
Operation DWT1327

4. Factors Affecting Operation of Deadweight
Testers

5. Maintenance Instructions

Shipping Instructions

List of Illustrations

Figure 1-1
Figure 1-2
Figure 2-1
Figure 5-1

and cylinder assemblies. One is a low pressure piston
having an effective area five times larger than that of the
high pressure piston. The low pressure piston is used for
making measurements below 2,000 psi (14,000 kPa). The
high pressure piston, with an area 1/5 that of the low pres­sure piston, is used to measure pressure through 10,000
psi (70,000 kPa). The weight masses are pre-measured
and identified with the pressure values they produce when
operated with the interchangeable piston and cylinder
assemblies.

Pressure calibration points produced by the deadweight
tester are accurate to within ± 0.1% of the reading certified
traceable to the National Institute of Standards and
Technoogy (NIST). The tester provides consistent, repeat­able accuracy, maintaining its pressure for an appreciable
length of time regardless of temperature changes, slight
leaks in the pressure system, or changes in volume of the
pressurized system due to movement of a Bourdon tube
or other device.

A hand jack set, three wrenches, spare O-rings, and a
special adapter for making connections to pressure outlets
that do not accommodate cone pipe seating, are included
with each unit.

All deadweight testers are supplied with lower and back

connection offset pipe assemblies, with pipe adapters for

1

⁄

4 NPT or

1

⁄

2 NPT connections.

An all metal, double-latched, top handle carrying case is
supplied with the complete tester for all fittings and attach­ments. Deadweights are packed in metal, double-latched
storage-carrying boxes.

2.1.2 Theory of Operation – DWT1305D

The theory behind a deadweight tester can be expressed
as simply as force acting upon a known area. Pressure
produced by the pump is distributed by the manifold, to the
base of a precision machined piston and to a device being
calibrated or checked. Pre-selected weights loaded onto
the piston platform are acted upon by gravity and develop
a force that is to be equally opposed by the fluid pressure
from the pump. When equilibrium is achieved, the pres­sure value is known, it being a direct result of the sum of
the forces from the weights, piston platform and the piston
divided by the effective area of the piston and cylinder
assembly.

With the DWT1305D two piston and cylinder assemblies
are supplied, one having an effective area 1/5 of the other.
When using the smaller piston and cylinder assembly, five
times more pressure is required to oppose the force of a
constant mass being acted upon by gravity. For this rea-

Figure 1-1 Omega Portable Dual Range Deadweight Tester – Type DWT1305

son the masses supplied with the tester are stamped with
two pressure values, the value being contingent on the
effective area of the piston and cylinder assembly selected.

2.1.3 Specifications – DWT1305D

Accuracy:

Combined tolerance of weights and piston and
cylinder assemblies within 0.1% of reading. Weight toler­ance within 0.05% of mass. Piston and cylinder is within

0.05% of rated mean effective area.
Deadweight: Non-magnetic die cast zinc alloy. Total
weight to produce maximum pressure of 10,000 psi
(70,000kPa) is 125 lbs. (56.7 kg).
Piston & Cylinder Assemblies: High strength stainless
steel piston and cylinder with brass collar and aluminum
weight platform.
Pump: Tw o stage, lever operated generates 10,000 psi
(70,000 kPa) with 28 pounds (12.7 kg) of force on lever
handle.
Pump Body: Aluminum, corrosion inhibited and coated
with baked blue epoxy finish.
Shuttle Valve: Stainless steel bypass valve that controls
rate of pressure increase and reduces operator effort
when working at high pressure.
Displacement Valve: A fine pitched threaded valve rod
permitting vernier adjustments to fluid volume and provide

precise pressure changes or adjustment of piston travel.
Limit stops prevent rod removal during normal operation.
Mounting: Four bench mounting holes located in base for
positive mounting to any level surface.
Instrument Connections: Tw o coned pipe assemblies
provide vertical calibration capability for back and lower
connected gauges. Standard

1

⁄4 inch internal NPT and 1⁄2
inch inter NPT fitting adapters are supplied.
Operating Fluid: DWT1305D – Light grade machine oils,
automotive petroleum base SAE 20 oils or other equiva­lent fluids suitable for use with Buna N O-ring materials.

1.5 pints required (.7 liters).

DWT1305DH – Most hydraulic oils of phosphate ester
base, brake fluids, skydrol, pydraul etc., suitable for use
with Butyl or Ethylene-Propylene O-ring materials. 1.5
pints required (.7 liters).

2.1.4 Certification:
Standard

– Certificate of NIST traceability
(accuracy/traceability statement only).
Optional (CAL-3) – Certification document includes actual
(as left) weight values for each weight and piston, piston
diameter values, environmental data and NIST test
numbers. Set includes numbered weights.

2.2 Product Description DWT1327D

Model Piston Assembly Piston Net

Number Pressure Range Piston Area Value Number of Weights by Value Weight

L-5 L-10 L-20 L-40 L-100

psi Type Low High Low High Low

High

H-25 H-50 H-100 H-200 H-500

lbs. kg.

DWT1305D-10
DWT1305DH-10 15/200 75/1000 5 25 1323--6027
DWT1305D-20
DWT1305DH-20 15/400 75/2000 5 25 132327032
DWT1305D-30 .

0625 in.2.0125 in.

2

DWT1305DH-30 15/600 75/3000 (.4032) (.0806) 5 25 132348539
DWT1305D-50
DWT1305DH-50 15/1000 75/5000 5 25 1323810548
DWT1305D-100
DWT1305DH-100 15/2000 75/10000 5 25 13231817580

Model Piston Assembly Piston Net

Number Pressure Range Piston Area Value Number of Weights by Value Weight

L-.5 L-1 L-2 L-4 L-5

kg/cm2Type Low High Low High Low High

H-2.5 H-5 H-10 H-20 H-25

lbs. kg.

DWT1305DM-20
DWT1305DMH-20 1/20 -- .5 2.5 112126329
DWT1305DM-100
DWT1305DMH-100 1/20 5/100 .5 2.5 112126530
DWT1305DM-150 .

0625 in.2.0125 in.

2

DWT1305DMH-150 1/30 5/150 (.4032) (.0806) .5 2.5 112147534
DWT1305DM-350
DWT1305DMH-350 1/70 5/350 .5 2.5 11211210548
DWT1305DM-700
DWT1305DMH-700 1/140 5/700 .5 2.5 21212617580

Model Piston Assembly Piston Net

Number Pressure Range Piston Area Value Number of Weights by Value Weight

L-.5 L-1 L-2 L-4 L-5

bar Type Low High Low High Low High

H-2.5 H-5 H-10 H-20 H-25

lbs. kg.

DWT1305DB-20
DWT1305DBH-20 1/20 -- .5 2.5 112126329
DWT1305DB-100
DWT1305DBH-100 1/20 5/100 .5 2.5 112126530
DWT1305DB-150 .

0613 in.2.0123 in.

2

DWT1305DBH-150 1/30 5/150 (.3954) (.0791) .5 2.5 112147534
DWT1305DB-350
DWT1305DBH-350 1/70 5/350 .5 2.5 11211210548
DWT1305DB-700
DWT1305DBH-700 1/140 5/700 .5 2.5 21212617580

Model Piston Assembly Piston Net

Number Pressure Range Piston Area Value Number of Weights by Value Weight

L-50 L-100 L-200 L-400 L-500

Pascal Type Low High Low High Low High

H-250 H-500 H-1000 H-2000 H-2500

lbs. kg

.

DWT1305DA-2000
DWT1305DAH-2000

100/2000 -- 50 250 112126329
DWT1305DA-10000
DWT1305DAH-10000

100/2000 500/10000 50 250 112126530
DWT1305DA-15000

.

0613 in.2.0123 in.

2

DWT1305-DAH-15000

100/3000 500/15000 (.3954) (.0791) 50 250 112147534
DWT1305DA-35000
DWT1305DAH-35000

100/700 500/35000 50 250 11211210548
DWT1305DA-70000
DWT1305DAH-70000

100/14000 500/70000 50 250 21212617580

Dimensions in ( ) are square centimeters

TABLE 2-1

2.2.1 Construction

The Omega Type DWT1327D Portable Test Pumps are
rugged, versatile pressure transfer standards, used for
testing, setting, calibrating or repairing pressure measur­ing devices with ranges up to 10,000 psi (70,000kPa). A
selection of high accuracy test gauges, with a precision of
±0.25% of span, are available as the standard to which the
device under test is compared.

The main component to the tester is a two stage hydraulic
pump containing a manifold which is pressurized during
operation. Integral to the pump is a shuttle valve that
allows the operator to regulate the speed of pressure
increase. One connection to the manifold has a straight
pipe with a precision test gauge attached serving as the
reference standard. A second connection to the manifold
accommodates a gauge or other pressure measuring
device to be calibrated or checked. Incorporated into the

manifold is a hand operated displacement valve that
allows small adjustments in fluid volume to be made with­out further operation of the pump handle or release valve.

Pressure values produced by the pump are able to be
clearly read to within ±0.25% accuracy of the span of the
precision test gauge selected for testing. A hand jack set,
three wrenches, spare O-rings, and special adapter for
making connections to pressure outlets that do not accom­modate cone pipe seating, are included with each unit.

Test pump accessories include lower and back connection
offset pipe assemblies, with pipe adapters for

1

⁄

4 and

1

⁄

2

NPT connections.

An all metal, double-latched, top handle carrying case is
supplied with the complete tester to hold all fittings and
attachments.

2.2.2 Theory of Operation – DWT1327D

Figure 1-2 Omega Portable Test Pump – Type DWT1327

Note: (97) Gauges are not provided with
the set and may be ordered separately.

The operating principle behind the DWT1327D Test Pump
is a simple form of comparison. Pressure produced by the
pump is equally distributed by the manifold to a test gauge
and to a device being calibrated or checked. The reading
of the test gauge serves as the reference to which other
device readings are compared.

Selection of the test gauge range is the determining factor
in establishing the precision to which a comparison check
is to be made. Test gauge accuracy is expressed as a per­centage of its span.

Proper selection of the test gauge range must be made to
minimize the amount of the unit error. If a 5,000 psi
(35,000kPa) range test gauge were used to test devices
whose span values were less than a fourth of the test
gauge range, the unit error of 12.5 psi (87kPa) would be
greater than 1% of the test pressure. Therefore, it is impor­tant to select a test gauge that has a full scale range equal
to or only slightly in excess of the pressure value to be
measured.

2.2.3 Specifications – DWT1327D
Accuracy:

1

⁄

4% of 1% of test gauge span.

Test Gauges: Omega PGT45L 41⁄

2˝ test gauges are

recommended.

Pump: Tw o stage, lever operated generates 10,000 psi
(70,000kPa) with 28 pounds (12.7kg) of force on lever
handle.

Pump Body: Aluminum, corrosion inhibited and coated

with baked blue epoxy finish.

Shuttle Valve: Stainless steel bypass valve that controls
rate of pressure increase and reduces operator effort
when working at high pressure.

Displacement Valve: A fine pitched threaded valve road
permitting vernier adjustments to fluid volume to provide
precise changes. Limit stops prevent road removal during
normal operation.

Mounting: Four bench mounting holes located in base for
positive mounting to any level surface.

Instrument Connections: Tw o coned pipe assemblies
provide vertical calibration capability for back and lower
connected gauges. Standard

1

⁄

4 inch internal NPT and

1

⁄

2

inch internal NPT fitting adapters are supplied.

Operating Fluid: DWT1327D – Light grade machine oils,
automotive petroleum base SAE 20 oils or other equiva­lent fluids suitable for use with Buna N O-ring materials.

1.5 pints required (.7 liters).

DWT1327DH – Most hydraulic oils of phosphate ester
base, brake fluids, Skydrol, Pydraul etc., suitable for use
with Butyl or Ethylene-Propylene O-ring materials. 1.5
pints required (.7 liters).

DWT1327DO – Distilled water with compatible corrosion
inhibitor. A .1% solution of sodium dichromate is a suitable
inhibitor. 1.5 pints required (.7 liters).

2.2.4 Certification:

Exclusively dependent upon certification provided with test
instrument.

3.0 SETTING UP THE TESTER