DIAPHRAGMACTUATED VALVES

Description RAF 68 & RAF 683 are piloted hydraulic valves activated by line pressure. Both pilots have spring- loaded membranes. One pilot is sensitive to upstream pressure & the other to downstream pressure. The combined operation of the two pilot valves sustains a constant pressure upstream of the RAF valve, & at the same time, reduce the downstream pressure to a preset pressure. The RAF valve opens or closes gradually to maintain both required pressures simultaneously.	Available Models RAF 68 - General Application two-way Pressure reducing/ sustaining valve. Pressure rating up to 16 bars. RAF 683 - Three-way pressure reducing/ sustaining valve. Plastic pilot is used for 2"-4" size with pressure rating up to 10 bar. For sizes 6"-12" a metal pilot is provided.
Applications Use the pressure reducing/ sustaining valve to define two pressure zones along a supply line, typically, along a downhill flow. Use RAF 68 for general water supply systems with medium pressure rating. The elaborated 2-way command with Raphael’s patented diaphragm enables smooth & precise pressure control. RAF 683 with plastic pilot valve is best for low pressure networks. Use RAF 683 for agricultural, domestic & rural water supply. The plastic materials provide high resistance to corrosion & cost- effective prices applicable in water treatment circulation & filtration manifolds.
Installation RAF Pressure Reducing/sustaining Valve is activated by the line pressure & controlled by two pilot valves. Both pilots include spring- loaded membranes. The sustaining pilot (the left one in the drawings) is preset to sustain the upstream pressure at a preset point. The reducing pilot (on the right) reduces the downstream pressure & maintain it at a lower preset level. In normal flow regime, the valve is partly open to sustain the upstream pressure & reduce the downstream pressure. It partly closes when the downstream pressure rises above the lower set point or when the line pressure drops below the upper set point. It opens again when the upstream pressure rises. In two-way configurations, the control chamber drains downstream, enabling faster & gradual opening without water spill. In three-way configurations, the control chamber drains out, enabling the valve to open fully.
RAF 68 - Two-way pilots		RAF 683 - Three-way pilots
RAF 68- control mode Manual: To open the RAF 68, close cocks 1and 2 & open the Vent. To close the RAF open cock 1 & close cocks 2 & Vent. Automatic: When line pressure is low, the pilots are positioned as shown. The RAF control chamber is connected to the line pressure, the RAF closes. When the line pressure rises & overcomes the spring of the sustaining pilot (the left one), the pilot’s membrane moves upward to open port 2. Then the RAF’s control chamber drains downstream through the right pilot. The RAF valve opens & reduces the upstream pressure. When the line pressure reduces, the left pilot recloses, as does the RAF. If the downstream pressure is greater than the set point of the reducing pilot (on the right), the reducing pilot’s membrane moves upward & closes its port 2. Again the RAF control chamber is connected to the upstream pressure & the RAF closes.		RAF 683- control mode Manual: Use the three-way cock to close or open the RAF by turning the handle to C or O, respectively. Automatic: The three-way cock should positioned in A. When the upstream pressure is low, both pilots are in the lower position as shown. The line pressure flows through ports 4-2 of the sustaining pilot the left one), flips the shuttle valve open, & flows into the RAF control chamber. The RAF is closes to sustain upstream pressure. When the upstream pressure rises above the set point, the membrane of the left pilot moves upward & opens its ports 2-3. The RAF control chamber drains this way (the shuttle valve remains open). Thus the RAF opens. When the downstream pressure rises above the preset reducing level (right pilot ), the right pilot membrane moves upwards. The line pressure then flows through its ports 3-2, flips the shuttle valve to the left & flows into the RAF’s control chamber. The RAF closes. The downstream pressure reduces.
Adjustment Use the needle valve a to control the RAF 68 operational speed. Adjust pressure set points by the adjusting screws of the pilots. See the list of available springs on the next page.
Typical Application RAF 68 valve sustains high pressure for industrial area upstream of the valve & reduces the downstream pressure.

	DIAPHRAGM ACTUATED VALVES	RAF MODELS	RAF General Information
\| Description \| Applications \| Available Models \| Installation \| \| Typical Application \| Specification Form \| Animation \|		RAF 68/683 Pressure Reducing /Sustaining Hydraulic Control Valve

Standard RAF 68	Standard RAF 683	Special Features RAF 60/63
Complete basic RAF valve as specified above	Complete basic RAF valve as specified above	Enamel/epoxy coating
Two metal pilot (2-way)	Two Plastic/metal pilot (3-way)-according to size	-
Self-cleaning screen filter	Self-cleaning screen filter	External heavy duty screen filter
Two 60 mm pressure gauge	Two pressure checkpoints	-
Three cock valves	Selecting cock (3-way)	-
Needle valve	Plastic shuttle valve (3-way)	-
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 68/683 Pressure Reducing /Sustaining Hydraulic Control Valve