Explore the Different Types of Water Meters and Understand Their Advantages and Disadvantages

There are a few different types of water meters used to measure water volume. Each type uses its own particular flow control and measurement devices, and differs in the method used to measure the water’s volume. The three most common types are displacement, positive displacement and velocity. Each type is suited to different applications and has its own advantages and disadvantages.

Displacement Water Meters

Displacement water meters measure how much water occupies a given space. They rely on a piston or mutating disk to control the movement of a magnet which activates the water volume register. The water pipes used in displacement water meters can range from as small as 5/8 inch up to two inches in diameter. Made of brass, high-impact plastic and stainless steel, the measurement register consists of a clear plastic bubble over an odometer-type or LCD display gauge. For measurements of less than 1/10 of a gallon, a sweep hand is also used on the measurement register. Displacement water meters are mainly used in residential and commercial applications as they measure small volumes of water at low flow rates to a high degree of accuracy. Also, these meters can be installed in separate units of a condominium or apartment to track individual water usage.

Positive Displacement Meters (PD Meters)

Positive Displacement meters, or PD meters, are the most common water meters for homes and small businesses. PD meters work by measuring the water that occupies a given space, similarly to displacement water meters. They provide accuracy of measurements obtained and are suitable for use with a variety of water pressures. PD meters are generally found in residential dwellings and small commercial properties, where accuracy and precision are paramount in order to ensure an accurate reading.

Velocity Water Meters

Velocity water meters measure the speed at which the water moves. The velocity of the water through the meter’s specific volume is measured and is then converted to units of volume, either in gallons or cubic feet. There are a few different types of velocity-based water meters, including single and multiple-jet water meters, turbine water meters, and compound water meters.

Single and multiple-jet water meters use the velocity of the water to measure the water volume. These meters have internal strainer grids to prevent the jets from clogging with particles in the water. Single and multiple-jet water meters are mainly used in low volume applications as the impellers can’t withstand high flow rates.

Turbine water meters, on the other hand, are used for larger water pipes. The water flow turns an impeller which rotates at a known speed in comparison to the water speed. These meters are used for high-volume commercial sites such as factories, large office complexes and in fire hydrants.

Compound meters measure the water usage when the water flow varies from high to low velocity. These meters have two measuring components and a valve, and are calibrated to adjust the accuracy of the measurement. The turbine meter handles high flow rates and the multi-jet meter handles the low flow. The utility reader adds the totals indicated on both meters to determine the total water usage.

Finally, electromagnetic or ultrasonic meters can also be used to measure water usage. Electromagnetic (‘mag meters’) meter measures water flow in or out of the system based on fluid induction principles, while ultrasonic meters send sound waves through water to measure its speed, and derive a water volume reading. These are used in large volume applications and for fluids other than water.

In conclusion, there are several types of water meters each with its own unique advantages, disadvantages and uses for different applications. Homeowners, business owners and owners of commercial properties should become familiar with each type and choose the one that best suits their needs.