R016600x

Steam Generator & Fluid Heater Installation Manual

Table 2-4: Clayton’s NPSH height requirements a

Model E-154 E-204 E-254 E-304 E-354 E-404

Feet

Meters

Model E-504 E-604 E-654 E-704 E-804 E-1004

Feet

Meters

18 13 13 18 30 15

5.5 4.0 4.0 5.5 9.2 4.6

15 18 18 30 10 10

4.6 5.5 5.5 9.2 3.0 3.0

a Requirements shown are based on Clayton’s standard reciprocating PD pump usage. Alternate pumps that require higher NPSH R are used on some generators. Check Clayton’s P & I D drawing for specific requirements.

NOTE Water flow is based on 44 lb. per hour per bhp. NPSH R s shown are for 150 psi de- sign steam pressure. Higher steam pressures could change these numbers.

2.11.3 Acceleration Head (H a ) Unlike centrifugal pumps that provide a smooth continuous flow, positive displacement pumps (typ- ically used by Clayton) cause an accelerating and decelerating fluid flow as a result of the reciprocating motion and suction valves opening and closing. This accelerated and decelerated pulsation phenomenon is also manifested throughout the suction pipe. The energy required to keep the suction pipe fluid from falling below vapor pressure is called acceleration head. For installations with long piping sections, this becomes a significant loss to overcome and must be carefully considered. If sufficient energy is absent, then fluid flash- ing, cavitation, piping vibration, noisy operation, reduced capacity, and shortened pump life can occur. To calculate the H a required to overcome the pulsation phenomenon, use the following empirical equation: where: H a = Head in feet (meters) of liquid pumped to produce required acceleration L = Actual suction pipe length in feet (meters) V = Mean flow velocity in suction line in feet per second (m/s) (See Figure 2-8 and 2-9, page 2-19 and 2-20, respectively.) N = Pump speed in rpm (See Table 2-5, below.) C = Pump constant factor of ... 0.400 for simplex single acting 0.200 for duplex single acting (J2 pump) 0.066 for triplex single acting H a = LVNC gk

0.082 for quadplex single acting (J4 pump) 0.041 for octoplex single acting (2xJ4 pump)

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Sect02_Genrl-xx4_t.fm

08/11/2016