DIAPHRAGMACTUATED VALVES

Description RAF 80 & RAF 83 are piloted hydraulic valves activated by line pressure. The pilot valve has a spring- loaded membrane which is exposed to the upstream pressure. The valve is normally closed. Only when the line pressure rises above a preset point, the RAF 80/83 opens to relieve the excessive pressure downstream without causing surge hazards. When the line pressure drops the RAF recloses.	Available Models RAF 80 - General Application two-way Pressure sustaining/ relief valve. Pressure rating up to 16 bars. RAF 83 - Agricultural & domestic Application three-way pressure sustaining/ relief valve. For 2"-4" size with pressure rating up to 10 bars.
Applications Use the pressure sustaining/relief valve to maintain constant upstream pressure & to avoid undesirable high pressure. This protection is required for most irrigation devices, domestic & industrial utilities. Use RAF 80 for general water supply systems with medium pressure rating. The elaborated 2-way command with Raphael’s patented diaphragm enables smooth & precise pressure control. The plastic pilot model, RAF 83, provides high resistance to corrosion & cost-effective price. It is best for irrigation, filtration manifolds, water treatment circulation & low pressure domestic applications.
Installation RAF Pressure Sustaining/Relief Valve is activated by line pressure & controlled by a pilot valve. The pilot includes a spring-loaded membrane. A sustained pressure is preset by adjusting the pilot retaining spring. The pilot is connected to line (upstream) pressure. The displacement of the pilot spring-loaded membrane due to upstream pressure defines the flow directions inside the pilot. When the upstream pressure is higher than the set point, the RAF valve is piloted to open. The excessive line pressure is relieved downstream. Otherwise the RAF remains closed, maintaining constant upstream pressure. In two-way configurations, the RAF’s control chamber drains downstream, enabling faster & gradual opening without water spill. In three-way configurations, the RAF’s control chamber drains out, enabling the valve to open fully.
RAF 80 - Two-way pilot		RAF 83 - Three-way pilot
RAF 80- control mode Manual: To open the RAF 80, close cocks 1 & 2 & open the Vent. To close the RAF open cock 1 & close cock 2 & Vent. Automatic: When the upstream pressure is lower than that of the sustained pressure set point, the RAF control chamber is connected to the line, as illustrated. The RAF is closed. When the upstream pressure rises above the set point, the pilot’s membrane is forced upward. Port 1 opens, the control chamber of the RAF drains downstream & the RAF 80 opens to relieve the excessive pressure.		RAF 83- control mode Manual: Use the three-way cock to close or open the RAF by turning the handle to the C or O positions, respectively. Automatic: The three-way cock should positioned at A. When the upstream pressure is low, the pilot’s membrane is in its lower position as illustrated. The RAF 83 control chamber is exposed to line pressure through the ports 4-2 of the pilot. The RAF closes to sustain the upstream pressure. When the upstream pressure is higher than preset, it overcomes the pilot spring & force the pilot membrane to move upward. Then ports 2-3 open & port 4 closes. The RAF 83 control chamber drains & the valve opens to relieve the excessive pressure downstream.
Adjustment Use needle valve a to control the RAF 80 operational speed. Adjust the sustained pressure by the adjusting screw. See table of available springs on the next page.
Typical Application RAF 80 valve sustains constant pressure for irrigation & relieves the excessive pressure to a reservoir below.

	DIAPHRAGM ACTUATED VALVES	RAF MODELS	RAF General Information
\| Description \| Applications \| Available Models \| Installation \| \| Typical Application \| Specification Form \| Animation \|		RAF 80/83 Pressure Sustaining/Relief Valve

Standard RAF 80	Standard RAF 83	Special Features RAF 80/83
Complete basic RAF valve as specified above	Complete basic RAF valve as specified above	Enamel/epoxy coating
metal pilot (2-way)	Plastic pilot (3-way)	-
Self-cleaning screen filter	Self-cleaning screen filter	External heavy duty screen filter
60 mm pressure gauge	Pressure checkpoint	-
Three cock valves	Selecting cock (3-way)	-
Needle valve		-
3/8" Reinforced Plastic tubes	8 mm Plastic tubes	Copper or stainless steel tubes

	DIAPHRAGM ACTUATED VALVES	RAF MODELS	RAF General Information
\| Description \| Applications \| Available Models \| Installation \| \| Typical Application \| Specification Form \| Animation \|		RAF 80/83 Pressure Sustaining/Relief Valve