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Installation Installing Two Pumps for Tandem operation <br />When greater flow rates are needed, two pumps may be required in the same piping system by means of a <br />manifold. If they are installed according to the illustration, a tandem system offers backup support so operations <br />can continue if one pump stops working. Install the pump as outlined above with the following additions. <br />1. if a siphon system is required, each pump must have 318 inch siphon vacuum line_ attached to the same <br />location on the siphon line (reference Figure 13). <br />2. WARNING! Adjust the Pressurstat (see "Adjusting the Pressurstat Line Relief Pressure" on <br />page 26) on both packers to maximum relief pressure by rotating fully clockwise. If maximum <br />r pump pressures are NOT a minimum of 5 psi below the Pressurstat relief setting then proper <br />check valves with pressure relief are required to be installed in the discharge line of each pump to <br />prevent product from being pumped through the pressure relief system of the adjacent pump <br />when it is not operating. Readjust the Pressurstat to the desired pressure relief value for proper <br />operation of the siphon system. <br />NOTE: Installation of a ball valve is recommended on the discharge side of the pressure relief check valve. This <br />will aid in troubleshooting and line testing. <br />NOTE: Figure 14 illustrates the requirement for in-line, pressure relief type check valves. It is not a <br />recommended guide for installation of piping downstream of the check valves. <br />As an option, install ball <br />valves downstream for <br />trouble shooting and <br />maintenance <br />Figure 14. <br />91 <br />The check valves shown installed in the <br />discharge line of each pump are <br />necessary to prevent product from being <br />pumped through the pressure relief <br />system of the adjacent pump, if that <br />pump is not running. This is because the <br />expansion relief valve operates at below <br />pump pressures. if check valves without <br />pressure relief were used, there would be <br />no provision for thermal expansion <br />between the valves and the dispensers, <br />d.0051-301.14.eps <br />