PLATFORM

High Pressure
Gas Piston Gaugefrom 100 kPa to 110 MPa (15 to 16 000 psi)Though liquid may migrate through thegas at the molecular level, no significant
contamination of the test system occurs.
As the liquid reservoir is contained in thepiston-cylinder module, the piston-cylinder
can be removed and installed in thePG7202 piston gauge platform with noloss of liquid from the reservoir.

DESCRIPTION/APPLICATIONSPG7202 is a member of the PG7000
family of reference level piston gauges
that covers the range of high pressure
gas up to 110 MPa (16 000 psi).
Operating directly in gas avoids
difficult to use liquid/gas separatorsthat add uncertainty to the measurement
process. PG7202's new, gas operated,liquid lubricated piston-cylinder
design overcomes the disadvantagesof lubricating the piston-cylinder withgas at high pressure. Performance is
not affected by gas cleanliness andpiston drop rates are even lower thanthose typically found in hydraulicpiston gauges.
PG7202 is combined with the GPC1
gas pressure controller to configure acomplete calibration system witheffort free gas pressure setting andadjusting (see GPC1 brochure).

GAS OPERATED,LIQUID LUBRICATEDPISTON-CYLINDER
The principle of operation of thePG7202 piston-cylinder is simple butvery effective. The measured gas pressure,Pg, is applied to the bottom of thepiston and to the top of a liquid
reservoir located around the cylinder.
The reservoir is connected to the gap
between the piston and the cylinder
through lateral holes in the cylinder,
allowing liquid from the reservoir toenter the gap. The pressure of theliquid in the gap, Pl, is equal to the gaspressure, Pg, plus the pressure resulting
from the liquid head, h. Therefore,
regardless of the gas pressure value,
the liquid pressure in the gap is always
higher than the gas pressure by theamount of the liquid head. Since h issmall and the space between thepiston and cylinder is typically lessthan 1 micron, the bleed of liquidfrom the bottom of the cylinder
towards the gas pressure is minute.
By design, any liquid accumulation
drops directly into a deadended sump.

Pg = measured gas pressure
Pl = liquid pressure
Pa = atmospheric pressure

Pl = Pg + ρlgh
Pl > Pg

All PG7202 piston-cylinder modules
can be delivered using Krytox®,
a fluorinated synthetic oil, to lubricate
the piston-cylinder for applications inwhich the system must be free ofhydrocarbons (e.g. when calibrating
instrumentation for oxygen service).

HIGH LINE, DIFFERENTIALPRESSURE
Two PG7202s can be used incombination to define low differential
pressures at elevated line pressures.
Contact DHI for more information.

UPGRADES OF TYPE 5200
PISTON GAUGESDH Instruments or Desgrange et Huot
Type 5200 and 5500 piston gauges
can be upgraded to PG7202 system byinstalling the piston-cylinders in new
PG7202 modules and using the existingType 5000 masses. See the data sheet"Piston Gauge Upgrades, 5000 to 7000"
for additional information.

NOTE: This brochure provides information specific to the PG7202 model of thePG7000 family of piston gauges. See the PG7000 Reference Level Pressure Standards
catalog for complete PG7000 information.

High Pressure
Gas Piston Gaugefrom 100 kPa to 110 MPa (15 to 16 000 psi)

PLATFORM

LIQUID LUBRICATED, GAS OPERATED PISTON-CYLINDER MODULES
AND MASS SETS
RangesDESIGNATORPRESSURE
TO MASS[p/kg]

PC-7200-100
PC-7200-200
PC-7200-500
PC-7200-1
PC-7200-2

Piston Only
[MPa]
[psi]

0.02
0.04
0.10
0.20
0.40

100 kPa
200 kPa
500 kPa
1 MPa
2 MPa

MAXIMUM PRESSUREMINIMUM PRESSURE*
Piston & Bell
[MPa]
[psi]

35 KG
[MPa]
[psi]

40 KG
[MPa]
[psi]

0.1
0.2
0.5
1.0
2.0

3.5
7.0
17.5
35.0
70.0

4.0
8.0
20.0
40.0
80.0

35153060153075
150
300

500
1 000
2 500
5 000
10 000* The minimum pressure point is defined by floating the piston only.
Piston mass is 200 g.

45 KG
[MPa]
[psi]

4.5
9.0
22.5
45.0
90.0

600
1 200
3 000
5 900
11 900

55 KG
[MPa]
[psi]

5.5650800
1 300 11.0
1 600
3 300 27.54 000
6 500 55.0
8 000
13 000 110.0 16 000

80 KG
[MPa]
[psi]

100 KG
[MPa]
[psi]

10.0
8.0
1 150
1 450
20.0
16.0
2 300
2 900
50.0
40.0
5 800
7 250
80.0 11 750 100.0 14 500
110.0† 16 000† 110.0† 16 000†† Full mass set cannot be loaded, maximum limited by maximum working pressureof PG7202 platform.

SPECIFICATIONSAll general specifications are identical to other PG7000 piston gauge models(see the PG7000 Piston Gauges catalog).

Piston-Cylinder Module Specifications
MODULENOMINAL AREA
[mm2]

TYPICAL DROP RATE
[mm/min]

MEASUREMENT UNCERTAINTYIN PRESSURE

PC-7200-100
PC-7200-200
PC-7200-500
PC-7200-1
PC-7200-2

98.1
49.0
19.6
9.8
4.9

0.10
0.15
0.20
0.25
0.50

± (2 Pa + 20 ppm)
± (3 Pa + 20 ppm)
± (7 Pa + 20 ppm + 0.15 ppm/MPa)± (10 Pa + 25 ppm + 0.15 ppm/MPa)± (20 Pa + 35 ppm + 0.15 ppm/MPa)

All pistons and cylinders are made of tungsten carbide.

ORDERING INFORMATION
Platform

Accessories

Designator

Part No.

Description

PG7202
PG7202401297401298Gas operated piston gauge
Gas operated piston gauge,
with motorized piston rotation

Piston-Cylinder Modules
Designator

Part No.

Description

PC-7200-100
PC-7200-200
PC-7200-500
PC-7200-1
PC-7200-2

401738401739401740401741401742

Gas P-C module
Gas P-C module
Gas P-C module
Gas P-C module
Gas P-C module

Mass Sets

To configure a complete PG7202 system, a means of setting andadjusting high gas pressure must be included. MPC1-3000
performs this function up to 20 MPa (3 000 psi). GPC1-16000 is
used for pressure up to 110 MPa (16 000 psi). A gas booster isused to supply the pressure controller with high pressure byboosting pressure from a standard gas cylinder. See the MPC1and GPC1 brochures for additional information.

Designator

Part No.

Description

MPC1-3000
GPC1-16000
Booster, gas
Booster, gas

401210401800401002400509Manual pressure controller
Gas pressure controller
75:1, with control kit
152:1, with control kit

See page 16 of the PG7000 Piston Gauges catalog.

Contact DHI for information for information on configuring ahydrocarbon free PG7202 system for dedicated use in hydrocarbon
free calibration systems.

PG7000, PG7202, GPC1 and MPC1 are trademarks of DH Instruments, Inc.
PG7000 piston gauges are manufactured under one or more of the following US patents:
5 142 483, 5 257 640, 5 331 838, 5 445 035.

Krytox is a registered trademark of E.I. du Pont de Nemours and Company.
Due to a policy of continual product improvement, all product specifications, descriptions andfeatures are subject to change without notice.

DH Instruments, Inc.

Tel 602.431.9100
Fax 602.431.9559
dhi@dhinstruments.com
www.dhinstruments.com

4765 East Beautiful Lane
Phoenix, AZ 85044-5318
USA© 2002 DH Instruments, Inc.

Printed in USA

Bro. No. 2010.2.A.3