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Gammon Gauge™

Direct Reading Differential Pressure Gauge

Why settle for less when you can have the tried and true original?

GTP-534

The Original Gammon Gauge

GTP-534-PB

Push-button Gammon Gauge

GTP-534-PB-PH

Peak-hold Gammon Gauge with Push Button Test Valve

GTP-8980

Gammon Gauge Control System

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. This feature eliminates the problem just as in the case of an unmanned facility such as a pipeline or hydrant system. Patent applied for.

Push-Button Test Valve

Hold the button in to relieve pressure under the piston. System pressure will force the piston down so the operator can observe motion. Erratic movement of the piston indicated contamination of piston and glass cylinder, requiring cleaning.

Note: This test releases about 50ml of fuel which can be collected in a cup or directed to recovery systems.

Pressure Relief Feature

Incorporated in all Push Button models is a thermal expansion 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 1/4 psi at system pressures to 300 psi

  • No subtraction calculation required

  • All models available in aluminum or stainless steel
  • Positive and negative surge pressure will not influence calibration

  • Multiple calibrations: PSI and Kpa (front face), Bar and KG/cm² (back face)

  • Every cylinder tested at 1200 psi
  • Rugged construction – suitable for vehicle or stationary use
  • Built-in gauge protection filter, 10 microns
  • Maximum operation pressure of 300 psi
  • Fittings: 1/4” NPT female, 1/4” BSP available
  • Temperature range of standard Viton GLT seals: -40°F to +400°F (-40°C to +204°C)
  • Ultraviolet light protection – film face cover prevents rays from degrading fuel in the glass tube
NOTE: The GTP-279 filter is obsolete. We offer a conversion assembly GTP-9515-1 (S/S) or GTP-9515-2 (AL). This is a complete replacement for the upper flange.

Calibration Testing

To meet API-1581, you should have a 3-way valve. Our 3-way valve meets this requirement and is used to check calibration 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 moment across its entire range. If the piston moves slowly, 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, all major 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 (Note: Do not clean with sandpaper or steel wool). Replace the o-rings and reassemble.

How to Order

Accessories & Replacement Parts

GTP-686

2″ pressure gauges

GTP-2233

filter element

GTP-672-1

scale: 0-15 psi

GTP-690-1

scale: 0-30 psi

GTP-547-1

glass tube kit

GTP-2200-23VG

cylinder o-ring

GTP-1271

ultraviolet shield

GTP-548

piston

GTP-552-8G

vent port

GTP-560-1

spring, 0-15 psi

GTP-560-2

spring, 0-30 psi

GTP-561

bleeder plug, aluminum

GTP-561-1

bleeder plug, stainless steel

GTP-581-1

cage, aluminum

GTP-537-4

cage, stainless steel

GTP-582

cage screw

GTP-600

strainer set

GTP-701

scale screw

GTP-703

retaining ring

GTP-805

socket plug

GTP-8306

installation kit

GTP-9341

nylon washer

GTP-9470-LH

proximity switch, left

GTP-9470-RH

proximity switch, right

GTP-552-8H

push button actuator body

GTP-9515-2

upper flange assembly, aluminum

GTP-9515-1

upper flange assembly, stainless steel

Maintenance and Rebuild Kits

GTP-9769

Gammon Gauge maintenance kit

GTP-9769-1

Gammon Gauge basic repair kit, 0-15 psi

GTP-9769-2

Gammon Gauge basic repair kit, 0-30 psi

GTP-9769-3

Gammon Gauge basic rebuild & maintenance kit, 0-15 psi

GTP-9769-4

Gammon Gauge basic rebuild & maintenance kit, 0-30 psi

Retrofit Kits for GTP-534

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. On Gammon Gauges™ without test buttons, a GTP-2305V 3-way ball valve can be installed.

GTP-552 series

options for stainless steel, aluminum, push button location, and peak hold

Gammon Gauge™ Control Systems

Protect Against Filter Element Bursting
Add a Differential Pressure Switch to the Gammon Gauge™
Sound Alarm – Stop Flow – Turn on Second Filter
Normally Open or Normally Closed, Fail Safe

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 operations 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.

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

Note: To meet IATA JIG Bulletin 58, order one of the “KS” options for key switch reset and test functions. The ATA-103 does not require this. For vehicle mounting, we recommend the weather-tight housing.

Notes:

  • GTP-8980 has a normally open switch. The switch closes upon high differential pressure. If the cable to the controller is cut, high differential would never be detected.

  • GTP-8980B has a normally closed switch. The switch opens upon high differential pressure. If the cable to the controller is cut, the system would go into alarm notifying the operator that something is wrong with the system.

  • If a system is purchased without the controller (no enclosure), both types of switches are still available. When a complete system is ordered with an enclosure, it is our policy to provide a GTP-8980B fail safe system unless otherwise requested. The difference is in the internal wiring and components in the controller.

How to Order

Examples

GTP-8980B-C-RH-12-B-0 is a differential pressure gauge with a normally closed switch as follows: push button aluminum gauge, 30 psi scale, switch on right side, 12 VDC, enclosure is weather tight which includes light and push to test feature, no solenoid valve, and low temperature o-rings.

GTP-8980B-C-RH-12-BKS-0 is the same as above except the enclosure has 2 key lock switches for test and reset per IATA JIG Bulletin 58.

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