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: -30^o to +160^oF, -34^o to +71^oC
  Low temperature seals: -90^o F / -68^o 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).

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.

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.

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

GTP-552-8PB
GTP-552-8PBF
GTP-552-9PB
GTP-552-9PBF

GTP-552-40
GTP-552-40F
GTP-552-40SS
GTP-552-40FS