11.2 Simple pressure systems

Question 1

As per the Simple Pressure Vessels (Safety) Regulations 1991 (SPV), simple pressure vessels have the following characteristics or limitations: 5

Answer 1

 Intended to contain air or nitrogen at a gauge pressure >0.5 bar, but less than or equal to 30 bar.  Not intended to be exposed to flame (i.e. ‘unfired’).  Manufactured in series, i.e. more than one vessel of the same type is manufactured during a given period by the same continuous manufacturing processes, in accordance with a common design of welded non-alloy steel, or non-alloy aluminium construction, or non-age hardening aluminium alloy.  A maximum working pressure (PS) of not more than 30 bar, and a PS.V (the product of PS and the vessel’s capacity expressed in litres) of not more than 10,000 bar litres.  A minimum working temperature of not lower than -50°C, and a maximum working temperature of not >300°C for steel vessels, and not >100°C for aluminium or aluminium alloy vessels.

Question 2

Schedule 1 of SPV details the essential safety requirements that qualifying vessels must satisfy. It also gives details of how the vessels should be categorised, the technical requirements to be satisfied, and the conformity assessment procedures to be followed. The ESR’s are presented in four parts:

Answer 2

Part 1: Materials Part 2: Vessel design Part 3 Manufacturing Process Part 4: Definitions and symbols

Question 3

The air receiver should either be constructed to withstand the compressor’s maximum pressure safely, or

Answer 3

be fitted with a safety valve and a pressure-reducing valve to prevent the receiver’s safe working pressure from being exceeded.

Question 4

Since air receivers are typically constructed out of carbon steel, they are subject to internal corrosion from water, which has condensed from the compressed air. Consequently air receivers are fitted with

Answer 4

automatic condensate drains or a manually operated drain valve to eliminate accumulated moisture.