API STD 681:1996 (R2010)

This standard covers the minimum requirements for liquid ring vacuum pump and compressor systems for service in the petroleum, chemical, and gas industries. This includes both vacuum pump and compressor design and system design. The design of the system is critical to the successful operation of the liquid ring vacuum pump or compressor. Close attention must be paid not only to the design of the ring liquid system but also to how it is integrated into the user's process. Although this standard covers minimum requirements appropriate for petroleum refinery service, purchasers may wish to consider pumps, compressors, and systems that do not meet all the requirements of this standard, based on specific nonflammable, nontoxic service conditions. Note: A bullet (--) at the beginning of a paragraph indicates that a decision by the perchaser is required. These decisions should be indicated on the data sheet (see Appendix A); otherwise, they should be stated in the quotation request or in the order.