Remote Vehicle Fuel Dispensers
2013-08-30 09:06:00
A concept in vehicle fueling, which is becoming more frequent, involves a secondary system dispenser designed to provide an alternate means of fueling a vehicle from the opposite side of the vehicle. The alternate means is a second dispenser plumbed from the primary (master) dispenser to a location on the opposite side of the vehicle.This concept is intended to shorten the fueling activity by providing a means to fill fuel tanks on the opposite sides of the vehicle simultaneously. This concept is predominant at service stations fueling saddle tanks on diesel trucks.
The second dispenser is referred to as a satellite or remote dispenser. The secondary dispenser relies on the pump and meter that is associated with the primary dispenser. The pump is generally a submersible located at the tank. The piping that is running to the remote dispenser is connected to the primary dispenser piping just after the product meter. The remote dispenser is electrically wired to be activated independent of the primary dispenser. However, in order to initially activate the satellite, the controls of the primary dispenser must be activated first.
This is typically done by removing the nozzle of the primary dispenser from its hanger/bracket and activating the “on” switch. The NFPA 30A Automotive and Marine Service Station Code expresses requirements for these units detailing how components must be pieced together. The intent of the code is that any device used to transfer fuel into a vehicle tank must have all the attributes of a dispenser.
A control shall be provided that will allow the pump to operate only when a dispensing nozzle is removed from its bracket or normal position and a switch on the dispensing device must then be manually activated to energize the pump and solenoid valves. The control shall also stop the flow of product when all nozzles have been returned to their brackets or non-dispensing position. Single action master (primary) and satellite dispensers shall have a clearly marked “pump stop” control at each fueling position. Controls on the satellite are not required to shut down product supply to a master dispenser.
Controls on a master shall shut off flow to a satellite dispenser. NFPA 30A 4-2.3 (1987 & 1993 Edition) is a general statement that the control must interact with the pump. Today’s remote dispensing locations normally have multiple devices fed from the same pump. The control at each dispenser has the ability to place the pump in operation or to stop the pump. When more than one dispenser is in use, the control does not directly start or stop the pump, it does however activate solenoid valves, internal to the dispenser, allowing or stopping flow of product to the respective hose. The control must stop the pump when all nozzles supplied by a submerged remote pump have been returned to their non dispensing position.
Piping from the primary dispenser to the remote dispenser must be provided with leak detection and catastrophic release detection as is required for the piping to the primary dispenser. A leak and release detection system on the piping from the tank to the primary dispenser capable of monitoring the piping to the satellite dispenser is acceptable.
This can be achieved if the solenoid at the satellite dispenser is located on the outlet side of the fire/impact valve at the satellite dispenser. The line leak detector for the primary line must have the ability to monitor the satellite line. A principle being that as either dispenser is activated, the leak detector will quickly “read” the line from the point of the leak detector to the solenoid in the satellite dispenser. If the detector senses a breach anywhere in the line it will activate flow restriction.