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Disassembly of the main valve
Chapter Two: Servicing an HPS Products Two-Stage
Valve
Chapter Two: Servicing an HPS Products Two-Stage Valve
Vacuum components must be kept free of both particulate contamination and of all foreign materials
which would have a significant vapor pressure. Before repairing the vacuum valve, prepare a clean
work station in a dust-free area. Tools should be clean, degreased, and devoted to precision
assembly.
Disassembly of the main valve
1-Vent both sides of valve
2-Turn off electrical power to the valve
3-Disconnect the air supply to the valve
4-Remove the screws holding the actuator cap to the body flange
5-Lift the actuator cap away from the body.
NOTE: These directions are for ammonium chloride buildup, which is soluble in water. Valves that
have aluminum chloride buildup must be soaked in cold water to minimize generation of HCl acid.
Refer to the Material Safety Data Sheet (MSDS) for proper handling of these chemicals.
In a new valve, the internal assembly should come off with the actuator cylinder. In a valve exposed
to contamination, remove the assembly by pulling upward on the stem. If the valve has heavy
contaminant buildup, try soaking the valve in water to loosen the solid buildup. Either way, remove
the internal assembly carefully, since all forces applied to the assembly are applied to the bellows,
which can be easily damaged. Do not overstress the bellows if you plan to reuse it. The full stroke
of a 4-inch diameter valve is 2 inches, therefore, not much effort is needed to compress the bellows
past its design specifications. Do not attempt to pry the assembly away from the body. Damage to
the sealing surfaces will result.
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