Water pressure reducer in a water supply system: purpose, design, adjustment rules

A water supply system consists of more than just pipes that transport water to supply points.It includes devices and mechanisms that allow stabilizing the operation of the pipeline.

One of these elements is a water pressure reducer in a water supply system - the device solves problems associated with changes in liquid pressure. In another way it is called a pressure reducing valve.

Let's figure out in what cases it is necessary to use a gearbox, how the device works, and what are the design features of different modifications. In addition, we will describe the installation technology and give an example of adjusting a pressure reducing valve.

What is a pressure reducer?

The water pressure reducer (WPR) is not installed on all systems. For example, in typical city apartments, where water supply is centralized, it cannot be found. But this does not mean that the pressure is not regulated, it’s just that the device is installed on a section of the pipeline up to apartment wiring.

Autonomous water supply, like centralized water supply, also needs pressure regulation. It is also necessary at industrial enterprises, farms, public institutions - wherever the water supply system operates. Let's take a closer look at what role the pressure reducing valve plays and whether it is really necessary.

Additional installation of RDV in the intra-apartment wiring ensures stable water temperature, regardless of the actions of neighbors in turning on/off the taps

Purpose and principle of operation

The mechanism, simple in design, nevertheless performs very important functions.It protects not only the water supply system itself from pressure changes, but also the equipment connected to it and sensitively responding to changes in water pressure.

Several reasons forcing you to install the RDV:

Only with stable water pressure heating equipment fulfills its service life and does not require frequent repairs. It has been noticed that if there is a reducer in the boiler piping that stabilizes the water pressure, the equipment works longer, and its spare parts do not wear out so quickly.

In urban high-rise buildings, pressure reducing valves are installed in nodes connecting common building systems with the central main line, as well as on hot water and hot water risers

The main function of a water pressure reducer is to regulate the water pressure in the pipeline, protect against water hammer and other troubles associated with a sharp increase or surges in pressure. Most often, the reducer is installed between the water supply valve to an autonomous or internal system and the point of consumption.

The operation of the pressure reducing valve is automatic adjustment, that is, for full operation there is no need to connect additional equipment or mechanisms. In the event of an increase in water pressure, the device independently reduces the indicators, due to which the water supply to boilers, boilers and taps is normalized.

Description of the work process:

• well water or a centralized system moves with a certain stable pressure;
• due to technical or other reasons, a pressure surge occurs, and there is a risk of failure of equipment connected to the water supply system;
• water under increased pressure enters the gearbox and acts on a spring or membrane;
• the valve cross-section automatically decreases, followed by a decrease in pressure;
• The liquid reaches the water collection points under pressure not exceeding the established standards.

The pressure surge that occurs in the water supply system is called hydraulic hammer.

It can happen in a multi-storey building or in a cottage, and the result of a sudden increase in standard parameters is expensive equipment or pipeline elements that fail.

A gearbox in a heating or water supply system is additional insurance against accidents, leaks, and flooding with unpleasant consequences for homeowners and sometimes “downstairs” neighbors

Thus, the WFD is the main tool for preventing undesirable consequences from water hammer, which you can independently install in your home water supply system.

The regulatory framework can be found in the documentation - GOSTR 55023, GOST 12678, methodological literature of the Scientific Research Institute of Plumbing.

Types and design features

Household regulators should be distinguished from industrial and commercial ones, and not only by size. For domestic ones, the productivity is much lower - on average 3 m³/h, while for industrial valve-reducers to reduce water pressure it reaches 15 m³/h and higher.

Household appliances are usually connected to the water supply system using a coupling method, and more productive ones are installed on main lines using flanges.

Almost all gearboxes are made from metals, more often from brass or brass alloys. The body is made in the form of a cross, the side pipes are intended for threaded connection to the pipeline, the top and bottom are for additional devices, for example, a pressure gauge.

There are two types of gearboxes that differ in design:

• piston;
• membrane

They are named after the main operating element located inside the body.

Piston gearboxes. The working part of the first category is a piston or piston assembly, which closes the valve under the influence of a spring.

Sample of a gearbox with a piston mechanism. Typically, devices of this type are designed for temperatures up to +80˚С, but the exact parameters are indicated in the product data sheet (+)

When water begins to flow under increased pressure, the spring presses on the piston, which reduces the flow area. Thus, the liquid in the inlet chamber is under greater pressure than in the outlet chamber. Consequently, the pressure in the wiring located after the gearbox will remain normal.

Piston pressure regulators are used for water supply and heating systems if the temperature of hot water and coolant does not exceed the upper limit established by the manufacturer.

Diaphragm reducers are considered more powerful, durable, wear-resistant, and less sensitive to poor quality fluid in pipes. However, their cost is higher than their piston counterparts.

Sample of a gearbox with a membrane mechanism. The long service life is explained by the design features - there are no parts inside the case rubbing against each other (+)

The operating principle of a diaphragm reducer is similar to that described above. Water enters the inlet chamber under high pressure and presses on the rod. Under the tension created by the spring and the rod, a gap is formed through which water enters the outlet with less pressure.

Membrane models, characterized by greater throughput and strength, are capable of reducing pressure from 25 bar or more to 6-7 bar or even lower.

If the inlet pressure is within normal limits, the liquid moves freely through the reducer without changing its parameters.

Installation and adjustment rules

If you have the skills to work with pipes, then you can install the RDV yourself. Beginners should not experiment; it is better to invite a plumber for responsible work.

Installation is carried out in the following order:

1. We purchase a couple of products - for cold and hot water, preferably the membrane type. We also prepare tools and consumables for sealing - fum tape or tow, lubricant. You will need keys and a thread cutting tool.
2. We turn off the water in the risers, notifying the neighbors in advance.
3. We install an inlet valve on the pipe after the meter before the shut-off valve. We use the threaded method.
4. First we fix the coarse filter, then the gearbox.
5. We seal the joints.
6. If necessary, install a pressure gauge. We position it so that the dial is clearly visible.
7. We connect the regulator to ball valve, seal.

After installation, we connect the water, turn off the ball valves and test the equipment.

One of the options for installing a pressure regulator in an apartment water supply system. The location of the RDV between the ball valve and the meter is considered technically sound and the most successful

The sequence of installing the regulator in the house is the same as for apartment installation.

Most pressure regulators are manufactured and sold with factory settings. The normal pressure is considered to be 3 bar. If you need to reduce or increase the specified parameters, you can make the adjustment yourself.

Pressure reducers have different designs, so adjustments are also made differently, according to the instructions. But usually one simple tool is required - either a screwdriver or a wrench

An example of do-it-yourself adjustment. Initially, the pressure on the gearbox with pressure gauge is set at 6 bar; it must be changed to 3 bar.

As a result, the pressure at the inlet and outlet should become different. At the inlet, as initially - 4.5 bar, at the outlet after adjustment - 3 bar.

This method is simple and can be done right on the spot. It is not necessary to remove the device from the pipe. Adjustment on the table is made when a new device is installed in place of an old device or when the gearbox is mounted for the first time.

It is more difficult to maintain a device without a pressure gauge, since it is impossible to control the indicators. Usually they twist it at random, guided by the result. But we still recommend using a pressure gauge temporarily by inserting it instead of the plug.

Conclusions and useful video on the topic

A professional look at pressure reducers:

Helpful theory:

Hints on adjustment may also be contained in the operating instructions for the device. If it is not there (which is possible when ordering a gearbox in China), you can guess how to change the parameters by carefully studying the design of the device.

In case of difficulties, we recommend contacting professional plumbers who know exactly how to quickly and correctly adjust the water pressure in the apartment. You can also consult with them on choosing a suitable regulator.

Share with readers your experience of using a pressure reducer for a water supply system. Tell us what you based your choice of device on and whether you are satisfied with the purchase. Please leave comments on the article, ask questions and participate in discussions. The contact form is located below.