API STD 681-2010 pdf free download

API STD 681-2010 pdf free download.Liquid Ring Vacuum Pumps and Compressors for Petroleum, Chemical, and Gas Industry Services.
1.4.13 Maximum discharge pressure is the maximum suction pressure plus the maximum dfferential pressure that the pump is able to develop when operating at the specified speed, specific gravity, and pumping temperature. 1.4.14 Maximum sealing pressure is the highest pressure expected at the seals during any specified static or operating condition and during start-up and shutdown. 1.4.15 Minimum allowable temperature is the minimum continuous temperature for which the manufacturer has designed the equipment (or any part to which the term is referred). 1.4.16 Normal operating point is the point at which usual operation is expected and optimum eficiency is desired. 1.4.17 The casing is the composite of all stationary pres- sure- containing parts of the unit, including all nozzles, seal glands, and other atached parts but excluding the stationary and rotating members of mechanical seals (see Figure E-1, Appendix E). . 1.4.18 Radially split refers to casing joints that are transverse to the shaft centerline. 1.4.19 Rated discharge pressure is the highest pressure required to meet the conditions specified by the purchaser for the intended service. 1.4.20 The rated operating point is the point at which the vendor certifes that performance is within the tolerances stated in this standard. Performance includes the following factors: capacity, power, efficiency, rotative speed, and rated suction and discharge pressures. 1.4.21 The shutdown point is a preset value of a parameter at which automatic or manual shutdown of the system is required.
1.4.25 Unit responsibility refers to the responsibility for coordinating the technical aspects of the equipment and all auxiliary systems included in the scope of the order. It includes responsibility for reviewing such factors as the power requirements, speed, rotation, general arrangement, couplings, dynamics, noise, lubrication, sealing system, material test reports, instrumentation, piping, and testing of components. 1.4.26 A wet critical speed is a rotor resonant frequency calculated considering the additional support and damping produced by the action of the pumped liquid within internal running clearances at the operating conditions and allowing for flexibility and damping within the bearings. 1.5 References 1.5.1 This standard makes reference to American standards; other international or national standards may be used as mutually agreed between purchaser and vendor provided it can be shown that these standards meet or exceed the American standards referenced. 1.5.2 The editions of the following standards, codes, and specifications that are in effect at the time of publication of this standard shall, to the extent specifed herein, form a part of this standard. The applicability of changes in standards, codes, and specifications that occur after the inquiry shall be mutually agreed upon by the purchaser and the vendor.
2.1 General 2.1.1 The equipment (including auxiliaries) covered by this standard shall be designed and constructed for a minimum service life of 20 years and at least three years of uninterrupted operation. It is recognized that this is a design criterion. 2.1.2 The vendor shall assume unit responsibility of all the equipment and all auxiliary systems included in the scope of the order. ●2.1.3 The purchaser will specify the equipmen’s normal and rated operating points on the data sheets. The purchaser will also specify any other anticipated operating conditions. ●2.1.4 Control of the sound pressure level (SPL) of all equipment furnished shall be a joint effort of the purchaser and the vendor. The equipment furnished by the vendor shall conform to the maximum allowable sound pressure level specified by the purchaser. ●2.1.5 Cooling water design conditicns will be specifed by the purchaser. Note that cooling water design parameters are particularly critical to the performance of liquid ring ma- chines. The lowest available cooling water temperature will result in the best performance, namely, capacity and suction pressure. The conditions in Table 2 are suggested guidelines.