Testing hydrants for water loss

During fires, any rescue team arriving at the scene needs additional sources of the main argument in the fight against fire - water. Such a resource can be taken from a nearby body of water or by shuttling between the storage facility and the source of the fire. And if the first option is not available, and the second is unacceptable, then the fence is made from the water supply using a fire hydrant. Its serviceability and ability to deliver the required number of cubic meters of liquid per second are important criteria in ensuring the safety of objects and human health.

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What is a fire hydrant

First, it’s worth understanding the definition itself. This device is an outdoor or underground type structure. It is built into the water supply system and has valves for convenient connection to a special column (if underground) or directly to a fire hose (if external). They allow you to efficiently and quickly collect water and extinguish fire without wasting time using a special tank. The steam generator, regardless of its shape and location, must provide the necessary pressure, as well as be accessible and serviceable at any time of the year.

The need to check fire hydrants

Most water intake devices in Russia are underground and are located in special niches - fire-prevention wells, which have the unpleasant feature of filling with water.

This happens for several reasons:

leaks in the SG housing if it is not closed correctly, as well as in the structure and pipes;
location of the well in the lowlands.

This not only leads to corrosion and premature failure of equipment, but in winter it makes access extremely difficult and prevents the rapid elimination of fire. In addition, if the base of the steam generator is located above the freezing point of the soil, the outlet valve and drain hole may freeze, which will lead to deformation and malfunction.

Frequency of inspection of fire hydrants

The PPB requirements establish the need to inspect steam generators twice a year, in weather specified by regulations and at above-zero air temperatures, in order to avoid the formation of ice.

An audit is carried out in the spring and summer. At the same time, the insulation installed in the fall is removed, access roads are inspected, and the general condition of the steam generator is inspected.
In the autumn-winter period, the well is checked and filled with water, insulation is carried out, and garbage is removed.

Nearby structures must have signs or any other signs indicating the location of the device, visible at night. Using a tape measure, the accuracy of the information printed on them is checked.

Photo from the website led-svetilniki.ru

The main purpose of the inspection is to check the technical condition of the elements.

The integrity of the hatch covering the well and the ease with which it opens. Also in winter, a special insulating box is required to protect against freezing.
Technical condition of the well.
The integrity of the SG housing, the absence of leaks and cracks leading to structural destruction.
Ease of opening the shut-off valves, their tightness.
Equipping the surrounding area and buildings with special signs indicating the location of the nearest water source.

Installation of a fire column

The operation of the fire hydrant is directly checked using a special column (KPA). It is installed in compliance with certain rules and precautions.

The device is screwed onto the PG nipple until it stops and the thread is completely closed. In this case, the square of its unlocking device (central key) must connect to the groove in the valve. The operation is carried out with the outlet pipes of the column closed.

The central key is turned half a turn to fill the KPA housing with water. The correctness of the actions taken can be determined by the sound of flowing water and its flow out of the hydrant through the drain. This is necessary to prevent the so-called water hammer, which can lead to the destruction of the hydrant and tearing of the column from the thread with unpleasant consequences for others.

After filling with water, the SG valve is allowed to open completely. You can start checking.

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In the case of a ground-based structure, the same sequence of actions is performed with the exception of installing the column.

Testing hydrants for water loss

The main and most important parameter for the quality of operation of the described device is the amount of water it can deliver in a short period of time. It changes due to corrosion and deposits on the inner walls of water pipes. To determine the technical condition of such communications and the impact on the fire safety of the facility, a fire hydrant is checked for water loss. Formally, what is being checked is not its actual flow (this is, essentially, a tap), but the water supply network. This is especially true for:

networks remote from the main highways (and therefore from pumps), where the required pressure may not be achieved;
areas with small pipe diameters;
old, renovated, dead-end, busy, long lines;
water pipelines near structures with a high fire hazard.

Photo from the website gov.cap.ru

The power of a fire hydrant is determined during the hours of maximum load on it. There are several ways to determine fluid loss.

Volume. For this purpose, a large (≥0.5 m³) measuring tank and a stopwatch are used, which is used to determine the filling time. The actual consumption is calculated using the formula Qf = W⁄t, where W is the volume of the tank in liters, t is the time required to fill it, in seconds.

Using a water meter. In this case, a regular fire nozzle is used, but with additional equipment in the form of a pressure gauge, as well as nozzles for measuring water loss at various diameters. Here the formula is used: Qф = P√H⁄√S, where P is the permeability of the nozzle, H is the pressure gauge readings, S is the resistance of the nozzle. The dependence of P and S on the trunk diameter (D) is shown in the table.