GB2318398A - Aircraft refuelling hydrant pit safety guard - Google Patents

Abstract

A guard 10 for an aircraft refuelling hydrant pit that will cause shut down of the valve 9 existing within the hydrant pit in the event of a vehicle making contact with the guard. Such event also causing an audible alarm 18 to sound and/or a visual alarm to illuminate. Also incorporating a fixed warning flag 22 attached to the upper part of the guard. If the guard is disturbed one more of three valves 14 are operated. These in turn activate a further valve which causes pressure in a hose 19 and valve 9 to be immediately dispersed causing the valve 9 to close. There is a reset button 16.

Description

AIRCRAFT REFUELLING HYDRANT PIT SAFETY GUARD This invention relates to the re-fuelling of aircraft through a pressurised hydrant system and in particular a safety device to prevent fuel spillage in the event of accidental damage to the hydrant pit and associated coupler.

It is common practice to re-fuel aircraft by means of a pressurised hydrant system with underground pipes leading from a remote tank farm and pumping station, terminating in a number of hydrant pits containing control valves and safety shut - down devices. The pits are typically located in the area where the aircraft loads and unloads passengers and safety is of paramount importance. Fuel leakage from the pit could result in fuel at pressure striking recently run and therefore hot parts of the aircraft engines which could lead to catastrophic fire.

The pits have flush fitting load carrying lids so that the aircraft may taxi and manouvre in the apron area when re-fuelling is not in progress and there can be considerable movement of vehicles servicing the aircraft, loading/unloading luggage, galley supplies, sanitation etc. etc.

Fuelling is normally undertaken with a hydrant dispenser vehicle carrying hoses, couplers, filtration and pressure control equipment. This vehicle will carry an inlet hose which connects to the hydrant (with flush lid removed) with a special coupler containing a pneumatically operated shut - off valve with a deadman control used by the vehicle operator. The hydrant pit also contains a shut - off valve that can be activated by a mechanical lanyard or by the pneumatic deadman control.

By way of further explanation only, Fig 1 is a plan view of a typical refuelling operation.

The aircraft to be fuelled 1, is located alongside the hydrant dispenser vehicle 2 connected to the aircraft by refuelling hose and coupler 3. The dispenser draws fuel under pressure from the hydrant pit 4 by means of inlet hose 5 and hydrant coupler 6, in which is located a pneumatically operated valve. The coupler 6 is connected to hydrant pit 4 in which is located a further pneumatically operated control valve. The operation is controlled by the vehicle/refuelling operator by deadman control 7, which, on release will close the valves located in coupler 6 and hydrant pit 4, said valves requiring air pressure to remain open.

There is concern that a vehicle could accidentally run into the pit while fuelling is in progress and cause mechanical damage resulting in considerable fuel spillage before the operator deadman system can react and close the pit valve.

The object of the present invention is to provide a guard around the pit that is sensitive to vehicle contact and which will cause the pit valve to close immediately, anticipating operator/deadman response and before any consequent damage takes place that could negate subsequent operator/deadman handle actions. The device can also be arranged to sense and react to circumstances, other than vehicle contact, for example a previously damaged coupling being undetected and thereby being caused to become disconnected from the hydrant in an uncontrolled manner. An audible and/or visible warning can be incorporated which will be activated if the device is triggered. A fixed visual warning can be added, such as a flag, to assist in preventing accidental collision.

A specific embodiment of the invention will now be described by way of an example and with reference to the accompanying drawings.

Fig 2 is a cross section of a hydrant pit and coupler with the guard in place.

Fig 3 is a pneumatic circuit diagram.

Referring to Fig 2 and Fig 3, the guard comprises a circular frame 10 attached to a body 11 supported from a base 12 by three equally spaced springs 13 such that any impact on the frame 10 from any direction will cause movement of the frame sufficient to operate any one or any combination ofthree pneumatic switches 14. Located in base 12 is a five port pneumatic valve 15 incorporating a reset button 16 and shuttle valves 17. An audible alarm 18 is connected to the five port valve 15. A second connection from the five port valve leads to the hydrant pit valve 9 by flexible hose 19. Air supply is from the hydrant/refuelling dispenser vehicle through deadman control 7 and terminating in flexible air hoses 20 and 21. Hose 20 is permanently connected to the hydrant coupler 6 and hence to valve 8. Hose 21 is connected to the inlet port of the pit guard. Hoses 19 and 21 have unique connectors such that incorrect connections are physically prevented. A warning flag 22 may be mounted on top of guard 10.

In operation, when refuelling is to be undertaken, the operator will place the Pit Guard in position over the hydrant pit and proceed to connect hose 19 from the guard to the pit valve 9, and hose 21 to the inlet connection on the Pit Guard. Activation of the deadman handle 7 will then cause air pressure to be applied to the inlet to the Pit Guard and therefore up to valves 14, to the inlet to the five port valve 15 and to the hydrant coupler valve 8. Valves 14 are normally closed, allowing pressure to pass on activation. Valve 15 is normally open and therefore on activation of the deadman control hoses 19, 20 and 21 will be pressurised, enabling coupler valve 8 and pit valve 9 to open, allowing fuelling to take place.

If, during the fuelling operation, the Pit Guard framelO is disturbed sufficiently to operate any one or more of valves 14 air pressure will be applied to valve 15 causing it to changeover such that pressure in hose 19 and pit valve 9 is immediately dispersed causing the pit valve 9 to close. At the same time air is diverted to to the alarm 18 which will be activated. The system may be reset by means of reset button 16.

Claims (9)

1. A guard for an aircraft refuelling hydrant pit that will cause shut down of the valve existing within the hydrant pit in the event of detection of the approach of a vehicle, or other circumstances, that would create a hazard by causing damage or disturbance to the equipment within and connected to the pit, during an aircraft refuelling operation.

2. A guard according to Claim 1 in which the closure of the pit valve is by release of pneumatic pressure normally holding the pit valve open.

3. A guard according to Claim 2 in which detection of the approach of a vehicle is by contact with a guard ring surrounding the pit.

4. A guard according to Claim 3 in which the said guard ring is mounted on a plurality of springs, with a plate in contact with a plurality of pneumatic switches, such that any movement of the guard ring resulting from vehicle contact will cause actuation of one or more of said pneumatic switches, thereby causing, through a change-over valve, release of pressure holding open the pit valve, which will therefore close.

5. A guard according to Claim 4 in which operation of said changeover valve will cause an audible alarm to operate.

6. A guard according to Claim 5 in which operation of said changeover valve will cause a visual alarm to operate.

7. A guard according to Claim 6 in which provision is made to reset the system after operation.

8. A guard according to Claim 7 in which a fixed warning flag is mounted on the top of the guard.

9. A guard for an aircraft refuelling hydrant pit according to any preceding claim substantially as described herein with reference to accompanying drawings Fig 1 and 2 and diagram Fig 3.