Monel Alloy 400 3/8" MNPT x FNPT Threaded End 6000PSI Steel Needle
Valve
What is Needle Valve:
| Type | Investment Cast |
| Body | ASTM 351 Gr. CF8M |
Packing | |
| Stem | 316 SS |
Handle | 304 SS |
Pressure | Maximum Pressure 6000 PSI |
A needle valve is used to make relatively fine adjustments in the
amount of fluid flow.
The distinguishing characteristic of a needle valve is the long,
tapered, needle like point on the end of the valve stem.
This “needle” acts as a disk. The longer part of the needle is
smaller than the orifice in the valve seat and passes through the
orifice before the needle seats.
This arrangement permits a very gradual increase or decrease in the
size of the opening. Needle valves are often used as component
parts of other, more complicated valves. For example, they are used
in some types of reducing valves.
Needle Valve Body Design:
One type of body design for a needle valve is the bar stock body.
Bar stock bodies are common, and, in globe types, a ball swiveling
in the stem provides the necessary rotation for seating without
damage.
Needle valves are frequently used as metering valves. Metering
valves are used for extremely fine flow control.
The thin disk or orifice allows for linear flow characteristics.
Therefore, the number of handwheel turns can be directly correlated
to the amount of flow.
A typical metering valve has a stem with 40 threads per inch.
Needle valves generally use one of two styles of stem packing: an
O-ring with TFE backing rings or a TFE packing cylinder. Needle
valves are often equipped with replaceable seats for ease of
maintenance.
