Spire Ultrasonic Flow Measurement for Submetering
Spire tackles two common problems related to large scale water measurement.
Energy conservation is an important goal for our customers. Hot water for heat and chilled water for cooling are conveyors of energy. Drinking water is also a valuable commodity. Many of our customers like universities, shopping malls, apartments complexes and commercial buildings are sub-metering water flows to better allocate costs. By allocating the costs to the users they provide economic incentive to conserve. Spire’s meters are perfect for metering these flows. They offer larger non-intrusive meters for metering an entire building as well as smaller in-line meters for sub-metering tenants within a building. The principal of operation of these meters is covered as a topic as well.
Large Pipe Water Metering
Many older building mechanical system designs did not factor in the need for metering. They have existing piping for the water and cutting the lines would mean an interruption of service that is often very inconvenient and costly. For these applications our customers are using Spire Non-Intrusive meters. These are very accurate and require no interruption of service.
For the customers interested in learning the energy consumed in heating or cooling water we recommend Spire’s BTU meters. These meters also come with temperature sensors that determine that are used to determine “Delta T” or the difference in temperature of inbound and outbound water in an area. These meters come with Modbus or BACNET protocol commonly used by building automation systems and provide units of measurement in BTU’s.
Small Pipe Sub-Metering
When our customers measure water to individual tenants the perfect solution is a small 1/2″-1″ inline ultrasonic flow meter. Traditionally these small meters have been mechanical but there are huge advantages to using this new technology. Two of these advantages are turn-down and stability, a measure of long term accuracy.
Turn down is the ratio of the smallest flow a meter can measure as a ratio to the maximum flow. This is a very important parameter for a flow meter because you need to know that you can accurately measure over the full range of your expected flow. In a building when a faucet is on you may have a few gallons a minute. When several faucets are on and you have a shower or two going simultaneously you may have several gallons a minute of flow. Your meter needs to measure that and most do. But what about when you have a leaky faucet or toilet? Can you meter measure that low flow? If it is mechanical it probably cannot! The water simply slips by the mechanical elements. It does not create enough force to turn the little gears. Spire’s ultrasonic meter does not have little gears to turn so it can measure minute flows just as accurately as the bigger flows. This is a great advantage over mechanical meters.
Mechanical meters also wear over time and that effects the second parameter, stability. We all know that moving water is wonderful at wearing down materials, even metals. We also know that when any solids move against each other over time they will wear. This erosion and wear causes considerable inaccuracy in mechanical meters over time. Not so for the Spire ultrasonic meters. With no moving parts there is nothing to wear so they stay much more accurate over time.
The principal behind ultrasonic flow meters is really very simple. Two transceivers are placed on the pipe, one upstream and one downstream.
Each transceiver sends an ultrasonic signal and receives a similar signal from the other transceiver. If the water (or other fluid) in the pipe is not flowing the time it takes those signals to get to the other side is the same. If there is flow then the signal getting to the downstream receiver will get there faster since the waves are carried by the flow current. Conversely, the signal getting the the upstream sensor will have to fight against the current so it will be slower. The difference in time of these transducers is related to the flow. It is that simple. There is some science related to the pulses, their frequency, width, power,etc. but the principal is pretty simple.
If you want more information on the principal of measurement or of the meters themselves then please download the presentation at the following link:
For even more information give is a call. We are always happy to help solve your metering and control problems.