What is a diaphragm solenoid valve?
A diaphragm solenoid valve (DSV) is a type of valve that controls the flow of water or other fluids in a plumbing system. A typical DSV has two sets of blades mounted on two pivots, one set on either side of the chamber. When a lever floats up, the blade sets are moved apart from each other, allowing fluid to flow through the chamber. This article will teach you all about how these devices work and what parts are used for making them.
High-level explanation of how a diaphragm solenoid valve works
In a DSV, each circle on the top is one of the six blades on which the piston rests. When a lever is placed in a certain position, it pushes down, causing one set of blades to close in and get closer to the other. This mechanism causes fluid to pass through an opening between the blades.
Diaphragm solenoids can vary wildly in terms of construction styles (an open-air version known as an “open diaphragm” or “open spring” can be found) and how they work (see notes at bottom). However, they are usually constructed of two pieces.
The diaphragm is the main part of the system
It consists of a flat disc that fits into a housing containing two blades and a piston. The bottom set of knives connects to the upper location across an opening in the housing; these two sets are called “phases”. A rubber washer keeps the blades from rubbing against each other but allows them to rotate relative to each other.
The top set connects to the upper phase on one side and the bottom phase on the other; this is called the “cotter pin” or “toggle pin” assembly. Each step is connected to a piston through a cylindrical chamber inside the housing.
The piston contains a rod that acts as an actuator
pushing down and out on the top set of blades, moving them away from the bottom. When there is no fluid pressure in the chamber, the piston rests tightly against a spring. However, when fluid pressure is applied to one or both of the phases (called “phasing” or “phasing down” respectively), they apply force to the piston that pushes it out of contact with its spring. This allows fluid to flow through an opening between the two sets of blades; if there were no pressure, then solid rubber seals would block this opening completely.
The cotter pin assembly is a simple mechanism that acts as a safety to ensure that the diaphragm only moves down and not up. When sufficient fluid pressure is applied to both phases, they push on the piston and force it away from its spring. When this occurs.
One of the two upward tabs will “slip” out of a hole in the valve body and be free to push against another spot. In effect, the cotter pin actuates itself; when there is sufficient pressure on its lower end (from both phases), it pushes against an upward tab which causes it to slip out of contact with another hole. Because pressure from above forces the cotter pin-up and in, it cannot push down and out on its bottom end. This ensures that the diaphragm only moves down; if the cotter pin were to be made in from below, it would retract (or “phase up”) against the spring.
The housing contains a set of springs that push
back on the piston when a certain fluid pressure is reached. An upper spring/lower spring pair are used as “overload” springs (also known as “burst” or “B” springs). The upper spring is also used as an intermediate-pressure “relief” spring; while it springs higher than the lower spring, it will be more resistant to compression when pressure on the system is too high (than the bottom spring). The diaphragm sits on both springs, pushing out against the piston when a certain pressure is reached. A lower spring and a coil spring are used in conjunction with each other; they become progressively more compressed as pressure increases in the system.
The “power supply” is a DC source that provides power to make the solenoid work.
Advantages of a Diaphragm Valve
The main advantage of a diaphragm valve is the good control it provides. For example, if an air tank is used in a pump system, the air pressure must be constant. In such cases, diaphragm valves are required. DSV’s are also useful when variable flow is required or when you need to control fluid flow remotely.
Diaphragm valves are also used when you need a high flow rate. If you have to channel fluid through a pipe, then diaphragm valves are more suitable than globe and gate valves.
Disadvantages of a Diaphragm Valve
Diaphragm valves are expensive and maintain free, but it is not easy to operate them. Compared to other valves, diaphragm valves can’t handle shock loading; this means that if there is an impact on the system, it will break down. Another disadvantage of this valve is that it requires a power supply for operation. If there is a problem with the electricity supply, then it becomes difficult to control the system through these valves.
Diaphragm-type solenoid valve working principle
The fluid travels in a cylindrical chamber between the blades in a diaphragm-type solenoid valve. The room is split into two halves by a central piston that pushes down on a lever that is attached to each blade. When the lever floats up from below, it pulls one blade out of the way so that fluid can flow through the chamber. When the lever floats down from above, it hurts both blades back together so that no fluid comes out of the opposite side.
Due to the diaphragm’s efficiency, it no longer needs to be energized by a DC power supply. However, its efficiency is not 100%, and this means that there is still a reserve of power to operate the solenoid. This means that it continues to work even when there is little or no flow of fluid through the valve. This can damage the valve body if there is no flow, so these valves are often built with a small motor called an “idler motor” to prevent this.
One of the most common diaphragm solenoid valves available can be seen in automotive air conditioning systems.