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PENN Controls Products Catalog

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Figure 73: Flow Chart, V46 Valve Example 1. The required flow of an R404A system is found to be 40 GPM (151 l/m). City water pressure is 40 psig (276 kPa) and manufacturer's table gives drop through condenser and accompanying piping and valves at 15 psi (103 kPa) drop through installed piping approximately 5 psi (35 kPa), leaving a net pressure drop available of 20 psi. 2. Draw a line through 40 GPM (151 l/m) - see dotted line, upper half of flow chart. 3. Size valves at 55 psi head pressure rise above opening point (valve is approximately 90% open). 4. Draw a line through 55 psi (375 kPa) - see dotted line, lower half of flow chart. 5. Available water pressure drop through valve = 40 - 20 = 20 psi (276 - 137 = 137 kPa). 6. Draw vertical line upward from this point to flow line - circle on flow chart marks this intersection. 7. Since the intersection falls between curves for 1 in. and 1-1/4 in. valves, choose the larger size. A 1-1/4 in. valve is required. 245 Refrigeration Products Catalog

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