Selecting the Proper AutoFlow Valve
3
Specify the Coil
Runout Pipe Sizes
Refer to the ASHRAE recommendations shown in the chart below. Some designers prefer to use 80 percent of the ASHRAE maximum.
ASHRAE Recommended Maximum GPM
see page 83 of F007 Design Guide4
Select the AutoFlow
Valve Spring Range
Two spring ranges are available for all AutoFlow valves: 2 to 32 psi and 5 to 60 psi. The first number is the differential pressure (D.P.) needed to achieve design flow. The second is the maximum D.P. where the design flow will be maintained. Following are some general rules on the selection of the spring range. In most cases the amount added to the calculated pump head is 4.6 feet (2 psi X 2.3 feet/psi).
- For direct return systems, if the total pump head is less than 110 feet, the 2-32 range can generally be used for all units.
- On reverse return systems the 2-32 range can be used for all units.
- For direct return systems with a total pump head exceeding 110 feet, the 5-60 range should be used onlyon units close to the pump to maintain control.
To calculate the spring range required for a specific terminal unit: Estimate the losses due to -
- pump accessories such as suction diffusers, check valves, etc.
- distribution pipe loss to the terminal unit
- terminal coil, ATC, and Y-strainer drops at design flow.
Time-tested, innovative solutions deliver leak-prooedf guaranteed performance for commercial, industrial and residential applications.
Flow Design is ISO 9001 Certified, is an active ASHRAE member, and is a leader in testing laboratory ratings.
© Copyright 2006, Flow Design, Inc.
Add a, b, and c and then subtract from the total pump head.
If less than 74 feet, use the 2-32 range. If greater than 74 and less than 138 feet, use the 5-60 range.
Example:
The total pump head is 132 feet and the total of a, b and c is 35 feet. 132 - 35 = 97 Use the 5-60 range since the remaining pump head is greater than 74 feet (32 psi).
5
Select the AutoFlow
Regulator Flow Rate
Using the chart below, find the available flow according to the size valve required and the system design flow. If the required flow falls between two available flows, round to the nearest flow listed.
Flows for sizes 3"-30" are available in five GPM increments
NOTE: 5", 18" and 24" flows available, see specific submittal