Chapter 4 REGULATORS 4-1 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

4-2 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e Functions of a regulator 1. To supply gas at a constant outlet pressure irrespective of varying inlet pressures within design limits. 2. Where necessary, to provide a means of shutting off the supply when no gas is being used. 3. To provide excess pressure relief where necessary.

Types of regulators 1. Service regulators 2. LPG regulators 3. Appliance regulators 4. Compensating regulators 5. Volumetric regulators 4-3 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Service regulators Usually fitted at the inlet side of a meter to reduce inlet pressures down to low pressure at the outlet. 4-4 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Operation of regulator –When the gas is turned on downstream, the pressure will drop, moving the valve off its seat. –When the valve moves the pressure on the underside of the diaphragm increases. –An increase in inlet pressure or drop in demand downstream will cause the valve to close. –A decrease in inlet pressure or an increase in demand downstream will cause the valve to open. –When the gas is turned off downstream pressure will increase, causing valve to close. 4-5 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

LPG regulators Fitted as close as practicable to the supply source, i.e. cylinder. Inlet pressure up to 1400 kPa. Outlet pressure at appliance 2.75 kPa. 4-6 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Pressure relief 4-7 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Appliance regulators If appliances are to burn the correct volume of gas, the pressure must be controlled. An appliance regulator is usually required to be fitted. 4-8 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Compensating regulators (1) There are two common types of compensating regulators: 1.Type A—uses a diaphragm and valve of equal effective area. 4-9 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Compensating regulators (2) 2.Type B—uses a second diaphragm with the same effective area as the valve Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Volumetric regulators This type can be used only on an appliance that requires a fixed volume of gas at a constant pressure, e.g. a single-burner appliance that is either full on or off Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Two-stage regulation Two-stage regulation uses two separate regulators to take advantage of higher pressures in the first stage to decrease pipe sizes Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Overpressure shut-off (OPSO) On larger installations and higher metering pressures, overpressure protection is achieved by using a device which shuts off the gas supply in the event of an overpressure situation. An overpressure shut-off (OPSO) is either an integral part of the service regulator or fitted separately. When an overpressure situation occurs, the diaphragm trips a valve, shutting off the gas supply. Overpressure protection may also be provided by using a monitoring regulator Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e

Regulators—Summary Purpose: To supply gas at a constant outlet pressure irrespective of varying inlet pressures within design limits. Common types of regulators 1. Service regulators 2. LPG regulators 3. Appliance regulators 4. Compensating regulators 5. Volumetric regulators 4-14 Copyright  2010 McGraw-Hill Australia Pty Ltd PowerPoint slides to accompany Puffett, Hossack, Stone, Burn & Miles, Gasfitting 2e