AIR LOCK RELAY |
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AIR LOCK is a reliable unit for achieving stay-put condition of control valves, on air supply failure, The air pressure is blocked inside the diaphragm chamber (or piston cylinder) of the actuator, when the supply air pressure falls below the desired set value. Quality materials are used and each unit is pressure and leak tested, to ensure long and trouble free operation. |
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DESIGN FEATURES |
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Wide cut-off range (1-4 kg/ cm2g or 2 - 8 kg/ cm2g) |
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Manual relieving provided |
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Corrosion-resistant construction |
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Aluminium or Stainless Steel material option |
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Mounting bracket provided for easy installation |
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Economic design |
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Minimum moving parts |
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| PERFORMANCE FEATURES |
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No leakage in pressurised condition |
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No drift in the cut-off value |
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Excellent stability and repeatability |
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Smooth action |
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Ideal for control valves and power cylinders |
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| ASSOCIATED BENEFITS |
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Utilises over 26 years of engineering design & application expertise |
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Long and trouble free service |
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Assured product Quality |
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PRINCIPLE OF OPERATION |
Air Lock Relay is designed such that when the header / supply air pressure falls below the desired set value (cut-off value) the Air Lock traps the air pressure in the diaphragm chamber of the actuator.
The cut-off is sat to a desired value by compressing the spring by spring adjusting screw. The cut-off value is adjustable and is generally set at a higher value then required for operation of the control valve.
If the actuator spring range is 0.2-1.0 kg/cm2g, the cut-off could be set at, say 1.4 kg/cm2g. Where number of control loops are involved, the relay could be set at, say 3.0 kg/cm2g.
The Air Lock needs an impulse connection from the air supply header, for operation.
The standard cut-off range (spring range) is 1-4 kg/cm2. However, cut-off range 2-8 kg/cm2 is also available. |
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Cut-off Setting |
Cut-off value has been factory adjusted. Should it be required to re-adjust the set value, it could be achieved either while the unit is already installed and connected to the system or separately on the test bench. Inlet supply air and the outlet pressure gauge should be available to re-adjust.
To adjust the cut-off value, remove the cap and adjust the spring adjusting screw until desired outlet cut-off pressure is achieved. Turning the adjusting screw clock-wise will increase the cut-off setting and turning it anti-clock wise will reduce the cut- off setting.
Please note that Air Lock has a differential pressure of 0.1-0.3 kg/cm2 higher than the cut-off pressure.
Replace cap securely after having re-adjusted the cut-oft-value. |
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Caution : Open Manual Relief Valve to vent actuator diaphragm chamber when control valve handwheel (override) is operated to avoid possible damage to the actuator diaphragm |
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| Technical Specifications |
Medium |
Air |
Port Size (Intel, Outlet, Supply) |
1/4" NPT (F) |
Supply Pressure |
9 kg/cm2g (125 psig) max. |
Material Of Construction |
Aluminium or Stainless Steel Option |
Cut-off Pressure Range |
1 - 4 kg/cm2g (14 - 56 psig)
2 - 8 kg/cm2g (18 - 114 psig) |
Weight |
0.9 kg in Aluminium, 2.0 kg in Stainless Steel |
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