User Guide

Insulation of Ball Valve Assembly

The ball valve should be completely insulated to minimize the effect of heat transfer and condensation at the actuator.

Caution:

The actuator itself must not be insulated. Doing so can result in excess heat or condensation within the actuator.

Temperature Limits for Ball Valve Assembly

When installing the ball valve assembly, observe the minimum and maximum temperature limits. Refer to the valve and actuator

specifications on pages 7, 12, 15, 18, 21, and 24.

Water System Maintenance

All heating and cooling systems are susceptible to valve and system problems caused by improper water treatment and system

storage procedures. Durability of valve stems and packings is dependent on maintaining non-damaging water conditions.

Inadequate water treatment or filtration, not in accordance with chemical supplier or ASHRAE handbook recommendations, can

result in corrosion, scale, and abrasive particle formation. Scale and particulates can cause scratches in the stem and packing,

and can adversely affect packing life and other parts of the hydronic system. Consult

EN-205, Water System Guidelines

Engineering Information,

F-26080, for futher details.

Sizing and Selection

Flow Coefficient (Cv)

When sizing a valve, you must select a flow coefficient (Cv), which is defined as the flow rate in gallons per minute (GPM) of

60 °F water that will pass through the fully open valve with a 1 psi pressure drop (ΔP). It is calculated according to this formula:

, where ΔP is measured in psi.

Since the flow rate through the heat exchanger is usually specified, the only variable normally available in sizing a valve is the

pressure drop. The following information in this section can be used to determine what pressure drop to use in calculating a valve

Cv. Once you have calculated the Cv, consult Table-2 to select the valve body having the nearest available Cv.

Note:

Metric equivalent.

• The metric measure of flow coefficient is k

, which is calculated according to the formula:

(where ΔP is measured in bar; 1 bar = 100 kPa).

• If the C

is already known, it may be converted directly to its k

equivalent: .

Two-position Control

Two-position control valves are normally selected “line size” to keep pressure drop at a minimum. If it is desirable to reduce the

valve below line size, then 10% of “available pressure” (that is, the pump pressure differential available between supply and return

mains, with design flow at the valve location) is normally used to select the valve.

gpm

PΔ

-----------=

h⁄

PΔ

---------------

1.156

---------------=