| 摘要 |
<p>A steam trap having a main valve member mounted in a control chamber and operable to afford and block fluid flow through the trap in response to actuation of a pilot valve by a thermal responsive element mounted on the main valve member is provided with means on the main valve member to channel a quantity of control fluid across the thermal responsive element for improving the response of the steam trap to changes in the temperature of the fluid flowing through the trap. In the illustrated embodiment, a quantity of control fluid is flowed upwardly through a passage around the periphery of the main valve member from the trap inlet and then past the thermal responsive element and through a central passage in the main valve to the trap outlet. Changes in the temperature of the control fluid expands and contracts the thermal responsive element to actuate the pilot valve for applying pressure forces on the main valve to cause the main valve member to engage and disengage its seat. Satisfactory performance of the trap is insured when the restriction to flow of the central passage in the main valve member is less than the restriction to flow of the peripheral passage of if the capability for mass flow through the central flow passage is greater than the capability for mass flow through the peripheral flow passage, taking into account the pressure differential across each of these flow passages. In another illustrated embodiment the thermal controlled pilot valve controls operation of a second pilot valve which in turn controls operation of the main valve to provide a multi-stage control of flow of condensate.</p> |
