Reservoir & Vented Receiving Sizing

Either a closed reservoir pipe or a vented receiver is required for proper condensate storage during the pump-down cycle of the pumping trap. Refer to the following tables for sizing.

For closed reservoir piping:
1. Determine condensate load.

Example:

  • The condensate load is 8,000 lb/hr (3629 kg/hr)
  • Refer to Table 10-1. Find the 8,000 lb/hr (3629 kg/hr) condensate load in column one. Move across the columns to find the proper pipe sizing

For vented receiver sizing:

  1. Determine the pressure from where the condensate is being discharged.
  2. Determine condensate load.
  • Refer to Chart 10-1 to find the pressure that corresponds to the discharge condensate pressure. For this example, use 15 psig (1.03 bar)
  • Follow 15 psig (1.03 bar) to where it intersects the "0" psig ("0" bar) curve. Move to the left from intersecting lines for the percentage of flash that will be created. For this example, it will be 3 percent
  • Multiply the 3 percent by the condensate load. For this example, it is 8,000 lb/hr. 8,000 x .03 = 240 lb/hr of flash steam (3629 kg/hr 3629 x .03 = 109 kg/hr)

Using Table 10-2, find the amount of flash steam in column one. Follow the table across to determine the sizing of the vented receiver.

Table 10.1

Inlet Reservoir Pipe Sizing for Closed Systems
Condensate Load
lbs/hr (kg/hr)
Reservoir Pipe Diameter (in)
2" 3" 4" 6" 8" 10"
up to Length of Pipe (feet)
1000 (453) 4 1/2 2 1 1/2
1500 (680) 7 3 2
2000 (907) 9 4 2 1/2
3000 (1361) 13 1/2 6 3 1/2 2
4000 (1814) 18 8 1/2 5 2 1/2
5000 (2268) 10 6 3 1 1/2
6000 (2722) 12 7 3 1/2 2
7000 (3175) 14 1/2 8 1/2 4 2
8000 (3629) 16 1/2 9 1/2 4 1/2 2 1/2 1 1/2
9000 (4082) 11 5 3 2
10000 (4536) 12 5 1/2 3 2
11000 (4990) 13 6 3 1/2 2
12000 (5443) 14 6 1/2 4 2 1/2
Note: When draining condensate from a single piece of equipment in a closed system, to achieve maximum energy efficiency, a reservoir should be installed horizontally above and ahead of the pump trap. Sufficient reservoir volume is required above the filling head level to hold condensate during the pump trap discharge cycle. The chart above shows the minimum reservoir sizing, based on the condensate load, to prevent equipment flooding during the pump trap discharge cycle.


Table 10-2
Vented Receiver Sizing for Open Systems
Flash Steam
lbs/hr (kg/hr)
Receiver
Diameter
Receiver
Length
Vent Line
Diameter
up to
75 (34) 4" 1 1/2"
150 (68) 6"
2"
300 (136) 9" 36" 2 1/2"
600 (272) 10" 3"
900 (408) 12" 4"
1200 (544) 16" 6"
2000 (907) 20"
8"
Note: When draining from single or multipment in an open system, a vented receiver should be installed horizontally abovle pieces of equipe and ahead of the pump trap. In addition to sufficient holding volume of the condensate above the fill head of the pump trap to hold the condensate during the pump trap cycle, the receiver must also be sized to allow enough area for flash steam and condensate separation. An overflow could also be added when required. The minimum recommended water seal is 12". The chart above shows proper receiver tank sizing based on flash steam present. See Chart 10-1 to calculate the percentage of flash steam at a given pressure drop.
Chart 10-1
Percentage of Flash Steam Formed When Discharging Condensate to Reduce Pressure





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