What is Positive Displacement Water Meter?
Positive Displacement 水道メーター is also known as Volumetric Water Meter. The two most common types are Volumetric Rotary Piston Water Meters and Volumetric Disc Type Water Meters (also known as Nutating Disc Water Meters). Positive displacement meters continuously divides the fluid into several volume units through a mechanical measuring element and then calculates the total flow by counting the number of these volume units.
BMAG Positive Displacement Flow Meter
BMAG produces high-quality positive displacement water meters that can be used in different scenarios such as industry, commerce, and home use.
Here are some of BMAG hot-sell positive displacement meters:
The following are the features of BMAG positive displacement flow meters:
- Positive displacement water meter bodies are diverse, including brass, plastic, and bronze.
- High protection class with IP68
- Measurement accuracy up to R400
- Can withstand hot water temperatures up to 90°C (194°F)
- Can be used with remote communications such as LoRa, LoRaWAN, NB-IoT, GPRS, M-Bus, Electromagnetic Pulse, etc.
- Flow range: 1/4 (High Flow Rate)~160 (Low Flow Rate)
Here are some of BMAG hot-sell positive displacement meters:
Advantages of Positive Displacement Water Meter
Positive displacement water meter has the advantages of high accuracy, ability to detect low flow, and flexible installation. The following content can give you a more detailed understanding:
The measurement error of positive displacement water meter is usually small and can be controlled within ±0.5% or even lower. Unlike velocity water meters that calculate flow indirectly, volumetric water meters calculate water consumption by directly measuring the actual volume flowing through the meter. Therefore, they can more accurately reflect the actual volume changes of water flow, improving metering accuracy.
Positive displacement water meters are suitable for low-flow detection and leak identification. Therefore, they are often used in homes, schools and hospitals. This is because the positive displacement water meter has a low starting flow rate and can start measuring even at extremely low flow rates. The starting flow rate ofpositive displacement meters with different sizes are:
DN15 (1/2″): 0.4gal/min
DN20 (3/4″): 0.6gal/min
DN25 (1″): 0.9gal/min
Positive displacement water meter has installation flexibility. On the one hand, positive displacement water meter usually has two types: horizontal and vertical, which can be selected according to the needs of the installation environment. On the other hand, positive displacement water meter has low requirements for the installation environment and does not require particularly complex installation conditions.
Positive displacement water meters usually do not require power to operate, which makes them reliable in environments without power supply. Positive displacement water metersmeasure water volume by using water flow to push the rotor to rotate. Its core components, such as the rotor and counter, are all mechanical components and do not require external power supply.
Positive Displacement Meter Typical Applications
Whether it is a home environment, a commercial environment or a factory, a positive displacement water meter has its place.
Home applications:personal residences, lawns, etc.
Commercial applications:office buildings, hotels, apartment buildings, etc.
Industrial applications:chemical industry, pharmaceutical industry, water treatment and wastewater treatment, food and beverage, etc.
Hot and cold water metering applications
Working Principle of Positive Displacement Water Meter
The core of the working principle of a positive displacement water meter is to use a measuring chamber or rotating part with a known volume to measure the water flow by filling and discharging the fluid one by one. Taking the piston positive displacement water meter as an example, the specific working principle can be divided into the following simple steps:
Step 1:After the water flows into the measuring chamber of the rotary piston water meter through the inlet of the water meter, the piston rotates in the measuring chamber.
Step 2:With each rotation, the piston cooperates with the wall of the measuring chamber to form independent cavities, dividing the fluid into small units of fixed volume.
Step 3:Since the volume of the piston cylinder (disc chamber) is constant, a fixed volume of water will be discharged each time the piston rotates a complete cycle.
Step 4:The counting mechanism (such as the fork and the rotating shaft) will record the number of times the piston rotates and finally display the total water consumption mechanically or electronically.
Volumetric Rotary Piston Water Meter VS Volumetric Disc Type Water Meter
In addition to the different internal structures, rotary piston-type and disc-type water meters also differ in performance and practical applications.
- Both rotary piston-type and disc-type water meters have high accuracy, but the sensitivity of the latter may be slightly lower than the former, especially in high or low flow conditions.
- The rotary piston type usually has higher installation flexibility and is available for horizontal and vertical installation. Disc type is usually recommended for horizontal installation.
- The rotary piston-type mechanical structure is more complex than the disc type and requires more maintenance. The disc type has a relatively simple structure and lower maintenance cost. However, the disc type is more susceptible to impurities than the rotary piston type. The durability and sealing performance of rotary piston-type is better and suitable for harsh environments.
