How do needle valves work?

Needle valves are referred to valve designs that are assembled with a small opening or gap adjunct to a plunger that looks similar to a sewing needle. Needle valves are often compared to a globe valve in terms of design and operation. As an alternative to the disk, a needle valve has a long, narrow point at the finishing part of the valve stem. Basically, they are small valves that are used in gas or liquid services. With a fine threading stem, the large seat area in the needle valve helps in clear-cut resistance flow. Keeping view that there are various kinds of needle valves in the market, it’s important to choose one according to the usage.

The purpose of a needle valve is to control the flow of liquid at a depressed rate. Needle valves help in managing the liquid flow into the sensitive gauges that can be potentially damaged as a result of sudden pressure of liquid. If you are to work in high pressure conditions, then hydraulic control nozzles are what you need the most.

Function

The primary purpose of a needle valve is to control the flow of liquid/gas to such an extent that its speed decreases gradually, and ultimately shuts off totally. Needle valves work great for throttle control, as they have a relatively small seating space than glove valves. They act as a guardian to protect the delicate gauges against high pressure. Furthermore, they are also used to manage the last part of a work cycle where it becomes compulsory to slow down the motion, and eventually put it to a halt.

Stem Threads

Typically, the stem threads in the needle valves fall into 4 categories: fine, coarse, non-wetted, and wet. Keep reading to understand the function of these threads:

·         Fine Threads: physically, fine threads have a very thin structure and they are situated close to one another. The purpose of fine threads is to control the needle valve stem so that is budges in the least amount.

·         Coarse Threads: Thickly structured than fine threads, coarse threads sufficiently spaced apart to permit flow and shut with the least exactitude.

·         Wetted Threads: Just as the name suggests, wetted threads are wet because they are open to the elements (fluid) that are constantly passing through the system.

·         Non-wetted Threads: As the name implies, these threads are not exposed to the fluid; hence, they remain dry and non-wet.

Seal                                     

A needle valve is composed of 3 basic types of seals: metal, metal-to-plastic and metal-to-metal. The plastic-to-metal and metal-to-plastic seal in a needle valve works great for controlling the flow of gas. However, the plastic-to-metal has a large seat space, which is desirable because gas molecules are more spaced out compared to liquid molecules. 

However, the metal-to-metal seal manages the flow of liquid.

Realizing the significance of needle valves in altering pressure, it’s important to buy them from a trusted and reliable supplier such as Seal Excel.  They are the best needle valvemanufacturers in the business that produce angle needle valve, instrument needle valve and more. Visit their website http://sealexcel.com/  to come across their comprehensive range of tube and pipe fittings.