Angle Information | Total Control

Valve Sizing

Valve sizing on a control valve is very important. The sizing graphs below are designed to assist in the selection of the correct valve size. When sizing a control valve the valve will control at a optimum between 20% and 80% capacity where 20% is the minimum flow and the 80% the maximum flow rate. This will prevent the valve from operating too close to the seat or from losing control during high flow.

Pressure Drop Chart

Valve Size	50 mm	80 mm	100mm	150 mm	200 mm	250 mm	300 mm	350 mm	400 mm
Minimum Flow	4.5 m³/h	6 m³/h2	11.5 m³/h	19 m³/h	39 m³/h	67 m³/h	78 m³/h	85 m³/h	122 m³/h
Normal Flow	44 m³/h	69 m³/h	129 m³/h	310 m³/h	508 m³/h	905 m³/h	1290 m³/h	1501 m³/h	1879 m³/h
Maximum Flow	60 m³/h	108 m³/h	168 m³/h	414 m³/h	710 m³/h	1120 m³/h	1354 m³/h	1940 m³/h	2200 m³/h

Normal flow @ 6m/s
Maximum flow @ 7.6m/s

System Sizing

Another important factor to remember is that control valves can be installed in a parallel system (to increase flow range) or series system (to increase pressure range).
With a low flow condition, the option can be to install a V Port. The V Port allows for smooth operation close to the valve seat, at low flow conditions.

Series system

When the pressure reduction ratio through a control valve exceeds 5:1, it is recommended to have two valves in series installed. The pressure reduction will then be done in two stages.