China globe valve manufacturers, globe valve suppliers, globe valve factory. ZGV standard Cast Steel Globe Valves are designed and manufactured to ensure leakage of less than 100 ppm (parts per million) of volatile organic compounds. Extensive base line laboratory testing (static and cycle testing) has been performed establishing critical design parameters necessary to achieve low emission sealing in the ZGV stem packing seal area and in the bonnet gasket sealing area, In-house testing procedure has been developed and is periodically performed to ensure that standard product design and manufacturing criteria consistently result in the ZGV Globe Valve meeting a maximum of 100 ppm VOC leakage prior to shipment.
In services requiring frequent cycling or with high pressure/temperature variations, live loading extends the service life between maintenance periods by requiring less frequent packing gland adjustments. Belleville springs are employed to provide constant packing gland stress. Lantern Ring and Double Packing Set Lantern ring with leak-off fitting connection and double packing stack is optionally available for critical services.
ZGV Steel Globe valves use a combination of dieformed flexible graphite and interbraided graphite in a predetermined arrangement to ensure an effective seal. Graphite packing achieves its maximum ability to isolate the atmosphere when it is contained within a chamber that is precise in finish and dimension. ZGV Globe valves are manufactured with stem finishes better than 32 Ra and stuffing box wall finishes for 125 Ra. In addition, stem straightness and taper are closely controlled.
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