Gate valve vs butterfly valve for water and district heating
On large water mains and district-heating networks the choice is usually between a gate valve and a butterfly valve. The butterfly valve is lighter and shorter; the gate valve gives a full bore. Here is where each one fits.
TAZ Engineering Team · · 6 min
Design
A butterfly valve closes the pipe with a disc that rotates 90 degrees, and the disc stays in the flow even when open. An open gate valve withdraws the wedge from the bore completely, so the flow path equals the pipe diameter.
Pressure loss and pigging
An open gate valve adds almost no resistance. A butterfly disc adds a loss that is minor on short runs but adds up on long transmission mains. Pigs and inspection tools cannot pass a butterfly valve; lines that will be pigged need full-bore valves.
Size and weight
A DN 600 wafer butterfly valve is several times lighter and shorter than a gate valve of the same size. That saves chamber space, reduces support loads and makes installation easier, which often decides the case at pumping stations.
Tightness, throttling and media
Rubber-lined butterfly valves seal water well at moderate temperatures. Hot water and steam need metal-seated designs such as triple-offset valves. A butterfly valve can throttle roughly between 20 and 70 % open; a gate valve cannot. Abrasive slurries wear butterfly discs quickly, and knife gate valves are usually preferred there.
How to decide
Choose a gate valve for piggable mains, minimum loss, on-site repair and high temperature with metal seats. Choose a butterfly valve where space is tight, sizes are large and coarse throttling is needed. TAZ makes both types; send the line data for a priced comparison.
Checklist
- DN and PN
- fluid temperature
- pigging requirement
- allowable pressure loss
- chamber space
- throttling need
- abrasiveness
- actuation