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Valve Components: Here’s What You Must Know

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Those seemingly simple valves employ a lot of physics inside those metal bodies of theirs. What you may think of as a simple open-and-close system is about to be a bit trickier than you thought. In this post, we’ll talk about the most important valve components and their functions.

If you’re an automotive detailer or industries from industrial and residential cleaning who’s trying to understand more about valves, you’ll find this post useful. 

You’d also be happy to know that our shop at MTM Hydro powered by Veloci has more than what you need. Let us know if you have any questions, and make sure to check the tips and tricks to keep our products safe. 

The Basic Valve: An Overview

A valve is a device that can regulate or control the flow of a fluid through pipes. For a device to be able to do that, it’ll need to withstand pressure, prevent fluid leaks, and have a mechanism that allows for fluid control. All of this leads to a plethora of components working together to provide the final result.

There are different types of valves out there. A few examples are:

  • Globe valves
  • Gate valves
  • Butterfly valves
  • Needle valve
  • Ball valves (sometimes referred to as plug valves)
  • Non-return valves
  • Diaphragm valves

Each of these valves controls the flow of fluids differently. Some of them share the same function but with a different design, like gates and globe valves. Nevertheless, there are a few basic components that are found in all valves. These are:

  • Body and bonnet
  • Disc and seat
  • Actuator
  • Stem
  • Packing
  • Trim

Valve Components

Valve Components: Explained

Here’s what each component does in detail: 

1. Body and Bonnet

The valve’s body is the valve’s main pressure boundary and the primary housing that contains all other parts of the valve.

The bonnet is the valve’s cover, making it another pressure boundary element. Some valves don’t have valve bonnets. Instead, the body is split into two parts that are threaded, bolted, or welded together. 

In some valves (like globe and stop check valves), the bonnet can have an opening where the valve stem passes, giving you access to the valve’s internal parts. This is useful when you need to repair any damage inside the valve. 

Together, the body and the bonnet resist the fluid pressure and, if properly constructed, should prevent any leakage. 

Valve bodies can be made into various shapes and from various materials depending on the intended use. Some of these include: 

  • Stainless steel
  • Bronze
  • Iron
  • Plastic

If the design includes a bonnet, the bonnet is often made from the same material as the body. 

2. Disc and Seat

The disc is the valve part that controls the water flow. As long as the disc is seated in place, it’ll be exposed to the full system pressure until the outlet is opened again and the disc leaves its place. 

Because of the constant pressure applied on discs, they’re often made from hard materials to resist wear.

The seat (sometimes known as the seal ring) acts as the disc’s seating surface. Not every design will have seal rings, as some of them have the body machined to act as the seating surface. 

3. Valve Actuator

The expression “close the water valve” that people use is practically incorrect. You don’t close the valve; you operate the actuator (also known as the handle) in a linear and rotary motion to close the valve.

When you use the actuator, you put the disc in or out of place, which, in turn, controls the fluid flow. 

Actuators could be manual handwheels or levers, but they could also be operated via motor operators, pneumatic operators, and hydraulic rams

Unlike the valve body, bonnet, and disc, the actuator is often outside the pressure boundary. The exception lies in some hydraulic or pneumatic cylinders. 

4. Stem

The stem is the connector between the disc and the actuator. When you operate the actuator, the stem puts the disc in or out of place to connect the fluid flow. Much like the actuator, it also lies outside the pressure boundary. 

Oftentimes, stems are forged and threaded or welded to the disc. This connection allows for some slight movement range to facilitate the disc’s seating on the seat or the valve’s body.

Some designs also manufacture the stem to be more flexible to allow the disc to position itself on the seat. However, these designs are more likely to damage the valve disc because of constant fluttering.

Note that stems have two types:

  • Rising stems
  • Non-rising stems

The difference between both types lies in the movement of the stem as the actuator is operated. 

Rising stem designs will have the stem screw above the actuator during usage. That rise is because the stem is threaded to a yoke that’s mounted to the bonnet. Alternatively, non-rising stems won’t rise above the actuator since the stem is internally threaded to meet the disc. 

5. Packing

Leakage can happen outside or inside the valve. The inside leakage is prevented by filling the space between the bonnet and stems with packing.

This packing can be composed of various materials like flax and teflon. The point is to seal the internal parts of the valve to minimize leakage.

6. Trim

The trim is a collective term used to describe all removable internal valve parts. These parts include:

  • Spacers
  • Discs
  • Valve seats
  • Guides
  • Springs


Valve Applications

Valve Applications

The quickest example of using valves in most people’s minds is using a water tap valve. However, they can be utilized in many other clever manners. 

For example, car detailers often use consolidated guns and lance systems to clean cars. This system usually uses a three-way ball valve. However, this would result in a lot of dismantling, wasted time, and lost spray.

A smarter application would be to use a two-way shuttle valve that allows the user to keep both the nozzle and the foam cannon in one place. With a single click, the user can switch between water or foam. 

One of the latest wash systems that utilize this design is the Mezzo Wash System by MTM Hydro powered by Veloci


The Verdict

As an automotive detailer, understanding valve components is among the many things you need to learn. 

And if you’re looking for smart applications of valves and various other auto detailing equipment, make sure to check MTM Hydro powered by Veloci

If you have any further questions, don’t hesitate to contact us today. We’re only a few clicks away.

ball valve Mezzo Wash System Valve Components

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