People think that in fire hydrant testing, they just have to open a hydrant and watch the water gushing out. But honestly speaking, even though it seems to be simple, there’s science behind it. So, if you want to check the water supply for fire sprinkler systems or fire suppression systems or just want to make sure you comply with the international fire codes, the right tools will help you do that without trouble.

In this section, we are going to list the must-have tools you need for a fire hydrant flow test and how they help you do the testing.

• Pitot Tube

• Gauges to measure Static, Residual, and Flow Pressure

• Diffusers

• Nozzle Adapters

Pitot Tube

A pitot tube is one of the flow test equipment that you will need in order to measure how fast the water is flowing out from the fire hydrant outlet. The water flow reading is called pitot pressure.

In general, it is like water flow testing to measure the pitot pressure as well as how much water supply is available during a fire emergency.

How Do You Use It?

You have to place the pitot tube just at the center of the water stream to measure the flow rate of the water (pitot pressure).

This is a must-have tool because it helps the fire departments determine if the test hydrant has the required water flow capacity set by the National Fire Protection Association (NFPA 291).

Static Pressure Gauge

The best analogy for measuring static pressure will be measuring your blood pressure when you are resting or measuring the air pressure in a soda bottle before you pop it open.

Static pressure is the water pressure inside the fire hydrant when the water flow rate is zero (which means no water is flowing).

You are going to use this gauge to measure the baseline pressure of the water supply before you start the hydrant flow test.

Residual Pressure Gauge

This gauge is used to measure the water pressure in a flowing fire hydrant. The main purpose of this is to measure the pressure drop when the water is used.

Why Do You Have To Measure the Pressure Drop?

Suppose there is a significant pressure drop between the static and residual pressure. In that case, it means either the water supply of the test hydrant cannot be relied upon or there is insufficient supply to fire sprinkler systems.

Flow Pressure Gauge

Now, flow pressure is the same as pitot pressure. Pitot pressure, as we have defined it before in this blog post, is the flow rate of the water when it comes out of the hydrant outlet. If the pitot gauge readings are high, the available water supply is very high.

Static, residual, and flow test hydrant flow tests are all important tests that the fire departments use to determine the adequacy of the water supply of that test hydrant for fire protection.

Two Hydrant Flow Test

Two hydrant-flow tests actually happen to be one of the most important concepts. The first fire hydrant is used for static and residual pressure measurements, and the other flow hydrant is used for the measurement of the actual flow rate of water.

The primary objective of this test is to verify the main capacity test of the water distribution system as far as the specific local fire codes as applied by the National Fire Protection Association (NFPA 291) are concerned.

Diffusers

If you are opening a residual hydrant outlet, then it is common that the water will come gushing out uncontrollably. It will damage the streets and also the sidewalks. A diffuser is a tool that will help you with this problem. Their main role is in the hydrant flow test location.

A diffuser is particularly useful when you are performing a large-scale fire hydrant flow test because it becomes difficult to manage such a large amount of water without a diffuser (unless you want the hydrant flow test layout to become a water park)

Nozzle Adapters

The nozzle adapters are pretty much in the same vicinity as the diffuser. This device also helps regulate the flow rate of water discharging from a flow hydrant. This will allow you to fit your pitot tube or the gauges for pressure reading tightly against the hydrant valve for accurate measurements using the nozzle adapter.

Properties of the hydrant cap slide into the same category as hydrant flow test equipment. These caps have gauges built directly into them to get static pressure readings without any other apparatus.

The Test Layout

Before conducting fire hydrant testing, an appropriate and suggested test layout has to be in possession to obtain satisfactory test results. No one starts a war without a battlefield!

Thus, one must know how many flow hydrants he or she is planning to test (if more than one hydrant), have all the necessary tools for fire flow testing in place, and also have the expected flow rate in mind before starting a fire hydrant testing.