Network Rail Case Study: The successful trial of the new
PBwel offer a number of kits to enable on-site gas and oil sampling at ground level. These are particularly useful when access to the Buchholz is restricted on site, which may make it difficult to fit standard equipment to draw Gas or Oil as required. Kits are suitable for 6mm Copper tube which can be readily obtained.
Each kit provides all of the fittings required to carry out the testing function required, be that oil sampling via ground mounted ballvalve, air injection via ground mounted Ballvalve (with or without retention of Buchholz mounted ballvalve) or Gas collection at ground level ballvalve (with or without retention of Buchholz mounted ballvalve). Lockable ballvalves are also available. All ballvalves have 1/8” BSPP male threads, supplied with a dust cap.
Double element relays are provided with a separate ballvalve to enable the injection of compressed air to be used for testing on site.
To test the operation of the alarm element, air from the PBwel Dry Air Pump or an air bottle should be admitted slowly so that the alarm element falls gradually until the switch operates.
To test the trip element, the valve controlling the Dry Air Pump or bottle is opened quickly so that the air rushes in, impinges on the flap and depresses it, operating the switch. The pressure required is dependent upon the equipment used.
Note: It should be appreciated that this test is no substitute for a proper works calibration of the relay
A handy alternative to the gas/oil sampling kits is the RAGA Gas Sampling Vessel. The RAGA provides a simple ground based auxiliary unit to the Buchholz, which is suitable to carry out the functions of gas and oil sampling. It also allows the volume of gas to be read easily from ground level where in certain conditions it may be difficult to see the dual window scales upon the Buchholz. This is done by a series of operations which exhausts the gas from the Buchholz chamber and transfers this to the gas drawing vessel (RAGA) where it will be displaced against the window scale.