About Definition Types for Equipment Items

Performance curve

• For a fan or pump, it represents the pressure rise (head) that the device can produce as a function of flow rate.
• For a valve or damper, it represents the pressure drop as a function of flow rate.

Specify at least four points of the curve based on the technical documentation provided by the equipment manufacturer. The more points you specify, the more accurately the curve is represented. Curves are different for each equipment type.

You can select the performance curve method for fans, pumps, valves, and dampers.

Constant Flow

Constant flow equipment produces the same, specified flow rate, irrespective of pressure (within a range). Enter a value of constant flow for the equipment.

You can select the Constant Flow method for fans and pumps.

K Factor

K factor represents minor losses, which means the pressure losses attributed to the flow flowing through fittings, valves, bends, elbows, tees, inlets, exits, enlargements, and contractions.

React Fluids handles the K factor in the three ways:

• For valves and dampers, you can select whether to use a K factor or other method
• For 2-way couplings and elbows, you can specify a K factor or use the K factor value computed by the solver
• For 3-way couplings (T couplings), you can only use the value computed by the solver because it is not possible to associate the k factor with each outlet or inlet.

You can select the K Factor method for valves and dampers.

Cv

Cv, referred to as Flow Coefficient, is used to specify the capacity of a control valve in imperial units.

where:

Cv - flow coefficient of a valve

Q - rate of flow (US gallons per minute)

SG - specific gravity of fluid (for water, it is 1)

ΔP - pressure drop across valve (psi)

You can select the Cv method for valves.

Kv

Kv, referred to Flow Factor, is a metric equivalent of Cv.

You can select the Kv method for valves.