1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-0a71 Submitted by: Wilson HarkinsSubject: Pneumatic Systems - Pilot-Controlled Pressure Regulator Loading Practice: Use a separate, hand-operated, spring-loaded, vented regulator in pneumatic system designs to provide refe
2、rence pressures for pilot controlled pressure regulators. Specify application in system/equipment specifications, requirements documents, and design policies and practices.Programs that Certify Usage: This practice has been used on the Apollo, National Space Transportation System (STS), and Pneumati
3、c Ground Support SystemsImplementation Method: This Lesson Learned is based on Maintainability Technique number OPS-09 from NASA Technical Memorandum 4628, Recommended Techniques for Effective Maintainability.Design of a pneumatic systems using vented pressure regulators offers the following maintai
4、nability advantages:a71 Requirement for a separate relief valve in the pilot-loading circuit is eliminated.a71 Logistics support requirements (materials, parts, tools) are decreased by elimination of additional relief valves.a71 System availability is increased by elimination of additional component
5、s and their maintenance/downtime requirements.a71 Elimination of components enhances maintainability and increases reliability.a71 Overall life cycle costs are improved by decreased maintenance and downtime requirements, and increased system availability.Pressure in pneumatic systems must be control
6、led. Primary points of control are downstream of the Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-source (compressor) and the system receiver (tank). Control of pressure is required downstream of the compressor for system safety and downstream of
7、the receiver to maintain a steady pressure source for efficient operation of other system components. Pneumatic systems use pressure regulators to provide this control. For those systems using standard dome-loaded (pilot-operated) regulators, this practice requires use of separate vented regulator f
8、or loading the pilot operated regulators. Figure 1 shows a regulator system with separate relief valves. A venting type regulator limits downstream pressure to a level lower than that of the upstream (receiver) pressure. It also acts as a relief valve for its leg of the circuit in the event of press
9、ure build up. This method eliminates the need for a separate relief valve in the dome-loading circuit. Figure 1 also shows an example of a vented system which illustrates this method.refer to D descriptionD Reference:1. KSC-SD-Z-0005A, Standard for Design of Pneumatic Ground Support Equipment.2. Par
10、ker-Hannifin Corp., Bulletin 0225- B1, Fluid Power.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Impact of Non-Practice: When pneumatic system requirements mandate the use of pilot operated pressure regulators, the use of vented pressure regulators
11、 to supply reference pressure is mandatory. This reduces the system component count and associated logistics requirements.Related Practices: N/AAdditional Info: Approval Info: a71 Approval Date: 2000-04-0a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
