1
The fl w control characteristics of the KOFLOC flow control valves are all represented by the flow characteristics graph shown in GRAPH1.
In the characteristics table (B), the flow changes substantially when the valve is turned slightly, which makes setting difficult and usage unstable.
Therefore, it is necessary to select ser-vice conditions as close to the status (A) as possible.
In the characteristics table (B), the flow changes substantially when the valve is turned slightly, which makes setting difficult and usage unstable.
Therefore, it is necessary to select ser-vice conditions as close to the status (A) as possible.
２.
KOFLOC manufactures valves individually to ensure they match the service conditions.
Simply select the type of valve and specify the supply pressure (primary pressure), outlet pressure (load pressure:
secondary pressure), and maximum operating flow rate, and then we will manufacture a flow control valve with the best control characteristics.
Even if there is no table or graph like the ones shown here, we can select the best valve.
The CV value used as the flow characteristics of needle valves and the like is explained below.
The CV value is a kind of flow coefficient, indicating the approximate flow through a valve when a certain pressure is applied.
P1: Primary-side absolute pressure [MPa·abs]
P2: Secondary-side absolute pressure [MPa·abs]
Q: Flow rate [m3/h]
ρ: Specific gravity (Gas: Air = 1, Liquid: Water = 1)
Simply select the type of valve and specify the supply pressure (primary pressure), outlet pressure (load pressure:
secondary pressure), and maximum operating flow rate, and then we will manufacture a flow control valve with the best control characteristics.
Even if there is no table or graph like the ones shown here, we can select the best valve.
The CV value used as the flow characteristics of needle valves and the like is explained below.
The CV value is a kind of flow coefficient, indicating the approximate flow through a valve when a certain pressure is applied.
P1: Primary-side absolute pressure [MPa·abs]
P2: Secondary-side absolute pressure [MPa·abs]
Q: Flow rate [m3/h]
ρ: Specific gravity (Gas: Air = 1, Liquid: Water = 1)
3
The CV value of a needle valve changes as shown in the GRAPH2 when the valve opening changes. Setting aside the control characteristics, the problem is the flow rate, not selection of an actual valve.
Therefore, the importance point is the maximum CV value shown in the GRAPH2.
Therefore, the importance point is the maximum CV value shown in the GRAPH2.
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This text shows the maximum CV values of all needle valves.
When the maximum CV value is substituted in the aforementioned equation to find Q, the maximum flow rate under the operating pressure and temperature conditions is derived.
However, application of this method becomes more difficult as the flow becomes more precise, so use it just as a rough standard.
Suppose 0.075 is the CV value, for example. Let's find the flow rate when the primary pressure (gauge pressure) is 0.1 MPa and the secondary pressure in the atmosphere (gauge pressure) is 0 MPa in cases where air of 20°C is to be controlled. In terms of absolute pressure, the gauge pressure will be 0.1 MPa · abs.
When the maximum CV value is substituted in the aforementioned equation to find Q, the maximum flow rate under the operating pressure and temperature conditions is derived.
However, application of this method becomes more difficult as the flow becomes more precise, so use it just as a rough standard.
Suppose 0.075 is the CV value, for example. Let's find the flow rate when the primary pressure (gauge pressure) is 0.1 MPa and the secondary pressure in the atmosphere (gauge pressure) is 0 MPa in cases where air of 20°C is to be controlled. In terms of absolute pressure, the gauge pressure will be 0.1 MPa · abs.
5
Therefore, the flow of 30 l/min can be controlled when the valve
operates between the fully-open and fully-closed states under the
above conditions.
operates between the fully-open and fully-closed states under the
above conditions.
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