internal view of the PECO Series 57 vessel

Gammon - Gauge

Static Discharge Reels
Hardware for Clay Elements
Gauge Control Systems
Back to Oil and Fuel Filtration

The Easy-Fueler
Deadman and Water Control Systems

The Peak-Hold feature registers the highest reading, locking the piston so the operator can see maximum differential pressure for the most recent fueling operation. Turning the large knob releases the piston so that it can return to zero.
With Push Button
Test Valve
Original Model
Push Button
In Front
Rotary 3-Way
Test Valve
Push Button
3-Way Test Valve
GTP-534 PB

Unique Features

Peak-Hold reading - The maximum differential pressure that is measured during an operation automatically locks the piston so that the operator will have that information without actually having watched the gauge at the time. After the reading has been seen, the operator releases the piston by turning a knob. It is usually impossible for the operator to see the gauge while refueling an aircraft so the highest differential pressure reading is rarely seen, just as a case of an unmanned facility such as a pipeline or hydrant system. This feature eliminates that problem.

Push Button Test Valve - hold the button inward to relieve pressure under the piston. System pressure will force the piston down so the operator can observe notion. Erratic movement of the piston indicates contamination of piston and glass tube, requiring cleaning.
Note: This test releases about 30 mL of fuel that can be collected in a cup or directed to recovery systems.

Pressure Relief Feature - Incorporated in all Push Button models is a pressure relief valve set at 300 psi to protect the gauge from excessive pressure if isolation valves have been closed.

Common Features of All Models of the Gammon Gauge

  • Read differential pressure directly at top of piston
  • Accurate within 1/2 psi at system pressures to 300 psi
  • No subtraction calculation required
  • All models available in aluminum or stainless steel
  • Positive and Negative Surge pressures will not influence calibration
  • Multiple calibrations: Front face - psi and kPa, Back face 0 Bar and kg/cm2
  • Every glass tube tested to 1200 psi
  • Rugged construction: suitable for vehicle or stationary use
  • Built-in Gauge Protection Filter, 10 microns
  • Maximum Operating Pressure: 300 psi
  • Fittings: 1/2" NPT female, 1/4" BSP available
  • Temperature Range: Standard Viton Seals: -30o to +160oF, -34o to +71oC
    Low temperature seals: -90o F / -68o C
  • Ultraviolet Light Protection: film cover prevents rays from degrading fuel in the glass tube.
  • Two scale ranges available, 0-15 and 0-30 psi. Any 0-15 psi gauge can be converted to 0-30 psi by ordering kit GTP-9104 containing a new spring and a new nameplate (scale).

System pressure gauges available to mount at top of all models

To add a 2" face diameter gauge, order:

GTP-686A for 0-60 psi GTP-686C for 0-160 psi
GTP-686B for 0-100 psi GTP-686D for 0-300 psi

  1. GTP-534-30-A-0 is an original model with 0-30 psi scale, aluminum construction and low temperature seals
  2. GTP-534-PB-15-S is a model with push button test valve with 0-15 psi scale, stainless steel construction and standard viton seals.
  3. GTP-534-PBF-PH-30-A-0 is a model with push button at the front, peak hold feature, 0-30 psi scale, aluminum construction and low temperature seals.

Note 1 A suffix D provides 2 selector valves, one at each connection. The ports on each valve are labeled A and B so that the gauge can be connected to measure differential pressure alternately on two different filters or on a filter having two stages.
Note 2 Same as note 1 but suffix G denotes 1/4 B.S.P. threads

Calibration Testing

To meet API-1581 and 1583, you must have a 3-way test valve. Our 3-way valve GTP-2305 and the Push Button Gammon Gauges meet this requirement and are used to check calibratiion as well as to check free movement of the piston.
  1. Establish flow in the system. The gauge should indicate a pressure drop.
  2. Push the test button. ������The piston should travel to the bottom of the scale.
  3. Release the button and stop flow in the system. The piston should return to zero.

If the piston returns to zero, you have not only calibrated the gauge, you have checked it for free movement across it's entire range. If the piston moves slowly or erratically, the filter (located in the top of the gauge) may be clogged and need replacement. This calibration technique is accepted by all major oil companies, airlines and military services worldwide. Gammon Gauges have been in service in virtually every major airport in the world for as long as 30 years and we have never heard of, or seen a single gauge go out of calibration. Occasionally a piston will stick after many years in service, but hand cleaning with "Scotch Brite" plastic abrasive will make it as good as new. (Do not use sandpaper or steel wool). Replace o-rings and reassemble.

Conversion of Existing Gammon Gauges

An existing Gammon Gauge can be converted to have the Peak-Hold and the Push Button Test Valve by replacing the lower flange of the gauge. Order as follows:

Standard GTP-534

Aluminum with Front Push Button
Stainless Steel
Stainless Steel with Front Push Button

add Push Button


add Push Button and Peak Hold


On Gammon Gauges without a Push Button, a GTP-2305 3-way ball valve can be installed.
Protect Against Filter Element Bursting
Add A Differential Pressure Switch To The Gammon Gauge
Sound Alarm - Stop Flow, Turn on Second Filter

If differential pressure suddenly increases or a facility is operated without personnel monitoring the differential pressure, filter element failure can occur. This new switch is unique. It adds differential pressure control at a low cost using a non-powered proximity switch. This simple double-sealed switch is ideal for use in PLC ( miniature computer) and relay controlled systems. The connection box is rated NEMA 4X.

Control options are also available if you don't plan to use an external control. We have weather tight and explosion proof versions.

We strongly recommend a 3-way test valve for properly testing the Gammon Gauge and Proximity Switch and / or system.

Conversion? Any Gammon Gauge can be converted to include the new proximity switch.

How to Order the Correct Part Number


GTP-8980-C-B12 is a different pressure as follows:

Push Button Gauge
30 psi scale
Aluminum material
12 VDC enclosure (weather tight)
with light and push to test feature

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