Portable Ultrasonic Flow Meters

Portable flow meters pack a lot of power into a small package and are ideal for HVAC, meter verification, flow surveys and other closed-pipe applications. Compact and easy-to use, you can hold and operate these units with one hand. Handheld flow meters utilize a clamp-on fixture design making measurement extremely easy even in the most difficult environments.

Ideal for flow measurement at fixed locations, clamp-on flow meters offer outstanding capabilities for accurate liquid flow measurement from outside of a pipe. Despite their portability, they offer NIST-standard performance up to 1% accuracy. Clamp-on meters are widely used in water resource management, chemical processing, hygienic liquid processing, high-pressure flow, and other applications where non-intrusive measurement is a must.

Designed for installation at a fixed location for long-term flow measurement without maintenance, insertion flow meters provide strong signal strength and exceptional signal quality. Accuracy as high as 0.5% can be achieved when properly calibrated.

High accuracy combined with plug & play performance, these flow meters offer excellent long-term stability and zero maintenance and can be installed directly into the pipeline. A great, reliable, flow meter that can be easily installed and operated.

For flow measurement applications in remote area where electrical power is not easily accessible, solar-powered flow meters are the ideal solution to a difficult problem. These flow meters have a self-contained solar panels and batteries, and provide low-power consumption for a long, maintenance-free life. Because they are usually installed in rural, rugged environments for long periods of time between servicing, all components, except transducers, are often housed in weather -proof, secure enclosure.

Used to obtain accurate thermal energy measurement of a liquid-based thermal energy production / transferring system, their non- intrusive design minimizes pipe cutting, moving parts, leaks, contamination, and pressure drop. Thermal energy meters are a perfect instrument for improving HVAC/building energy efficiency, energy production and transfer, and monitoring geothermal or solar-thermal systems.

Today's next-generation BTU meters are designed for residential and commercial applications, and utilize the latest technology in ultrasonic flow measurement. Their advanced designs have no moving parts and provide reliable, wear-free, stability over time. With a long life span typically reaching 15 years or more, heat meters usually include an automatic meter reading (AMR) system, allowing you to easily manage building resources.

Ultrasonic water meters offer cost effective water measurement over a wide range of commercial and residential applications. A high measurement dynamic and zero moving parts offer wear-free water measurement, precision, stability, and a very long service life.

Magnetic flowmeters are designed for liquid applications where accuracy is a critical requirement. Magnetic flow meters are commonly used to measure the volume of conductive liquids, such as water, sewage (including raw sewage), slug, salt water, acid, alkali, and others.

Today's advanced ultrasonic flow meters enable the accurate measurement of liquid flow across a wide variety of process control, water resource management, and energy consumption applications. But for accurate measurement in even the most remote areas, the use of wireless or GPRS Telemetry is becoming more common to enable consistent monitoring of water and other liquids where it wasn't possible before.

GPRS or General Packet Radio Services is a wireless communication service that is used for the wireless, continuous transfer of data. This technology has been widely adapted for use by water management professionals for tracking and monitoring water and other liquids in remote terrains where traditional instruments would prove impossible to implement and maintain.

The benefits of wireless telemetry in flow measurement applications are clear; specifically they allow for the accurate, continuous measurement even in the absence of electricity or alternative power supplies. These systems can be run on batteries which can be replaced over extended periods of time, or, can operate by small solar panels when they are installed in open, outdoor locations. The power and flexibility of wireless telemetry provides a foundation for continuous and consistent data signaling and capture, 24/7.

GPRS-based data management systems offers accurate, affordable solutions for remote metering of flowmeters, temperature sensors, pressure sensors, level sensors, BTU meters, etc., in real-time. Some of these systems provide web-based reporting and data visualization via secure portal or a mobile device. Typical components of a GPRS Telemetry flow metering system can include:

1. Wireless meter

Ultrasonic or magnetic meters with built-in GPRS wireless modem, automatically transmiting flow data to the data center on a regular basis. A SIM card can be inserted into the modem, with proper support of GPRS data service from your mobile service provider.

2. GPRS Wireless Service

Provided by your cell phone company, the GPRS technology transmits data from the meter to the data center server via wireless connection. Each meter requires a wireless connection by inserting a SIM card into the wireless modem of the meter.

3. Data Center Server

The GPRS wireless network sends meter data to the data center server, which provides data security, UPS and backup protection, static IP address, gateway, and firewall protection. The server software automatically collects data from all the remote meters, and saves data to a standard SQL database.

4. Interface Software

This software communicates with the data center server via the Internet, and displays data through a graphical interface, where it can be viewed, saved, manipulated, and out for print.

5. Web Portal (optional)

Secure customer portals can be deployed so that data can be viewed anytime, anywhere from remote computers or secure mobile devices.

The most commonly used ultrasonic flowmeter is the transit-time, single-path flowmeter due to its proven accuracy, flexibility, and low cost. Depending on the applications, the selection of the right type of flowmeter may vary. You may need to answer the following questions before making the final decision.

1. Is the pipe full? All ultrasonic flowmeters require that the pipes being measured are full of liquid. There are some effective approaches and available work-arounds for working with partially-full pipes, be sure to consult with the manufacturer or a factory trained technician.

2. Does the liquid have particles more than 200ppm and a particle size larger than 75um (the number may be different for different manufacturers)? If yes, you might want to consider using the Doppler principle.

3. Does the liquid temperature (particularly high heat applications) fall into the transducer temperature range?

4. Press range in the pipe (if you selected a wetted transducer)?

5. What is the desired level of measurement accuracy? In general, multi-path provides more accurate measurement than single path transducers, flow cell is better than insertion, and insertion is better than clamp-on. However, if you have on-site calibration facility, the story will change.

6. Do you want the capability of moving the flowmeter instrument from one location to the next? If so, consider a portable/clamp-on solution.

7. What output signals do you need? Analog? Digital? RS232? Data logger?

8. What are your safety requirements and considerations? Not all flowmeters can meet the specific safety requirements of all applications, be sure to consult with the manufacturer or a factory trained technician.

9. What is your pipe size range? Pipe material? Lining? Age?

10. What is your flow rate range?

11. Do you have enough straight pipe length? In order to guarantee the desired accuracy, it is normally recommended to have straight pipe equal to 15 times your pipe diameter at the measuring site. If there is a pump or valve on the upstream, the straight length should be increased.

12. What is your budget?

Every flowmeter manufacturer utilizes these standard technologies and principles. As a result, there are a variety of brands on the market, and almost all flowmeter vendors provide some level of application expertise or professional services group that can answer your questions. Regardless, a thoughtful combination of quality, accuracy and cost should be the guiding criteria when selecting a manufacturer or manufacturer's rep.

Today's advanced ultrasonic flow meters enable the accurate measurement of liquid flow across a wide variety of process control, water resource management, and energy consumption applications. To select the right ultrasonic flowmeter for your specific liquid application, you must first understand the four basic ways in which ultrasonic flowmeters are classified.

1. Measurement principle: Transit-time vs. Doppler

Transit-time flowmeters are based on the time difference between upstream and downstream sound propagation intervals, and provide one of the most reliable and time tested measurement principles available to date. This approach provides very good accuracy (±1-2%), and works well for clean flow applications or flow with minor particles. Applications include pure water, sea water, wash water, sewage, process liquids, oils, chemicals, and any homogeneous liquids which are capable of ultrasonic wave propagation.

Doppler flowmeters are based on the Doppler Effect. They work well with suspension flows where particle concentration is above 100ppm and particle size is larger than 100um, but less than 15% in concentration. Doppler is easier to make and less accurate (±5%), thus, it is cheaper than a transit-time flowmeter.

2. Device Portability: Handheld vs. Wall-mount

Handheld (or portable) flowmeters are effective for flow survey, HVAC, and other applications where mobility is a critical requirement. Some handheld flowmeters can be deployed as long-term measurement solutions when and if the environment is accommodating.

Wall-mount (or fixed installation) flowmeters are more suitable for applications such as process control and long-term continuous flow monitoring. The instrument enclosure is often weather-resistant or explosion-proof. These types of meters are usually cheaper than handheld devices because they are normally ordered in large quantities.

3. Transducer installation: Clamp-on vs. Wetted

Clamp-on flowmeters are non-intrusive, easy to install and easy to maintain. The transducers are mounted outside of a pipe, and don’t require the cutting or drilling of the actual pipe. Clamp-on transducers are nonintrusive and therefore cause no pollution or pressure drop in the liquid being measured.

There are two varieties of wetted flowmeters, insertion and flow cell (inline type). Insertion flowmeters require the pipes to be drilled to install the transducers. However, a number of manufacturers provide hot-tapping tools which allows for the transducer installation without depressurizing the pipe or shutting down the flow.

Flow cell, also called spool piece are installed in line with the pipe, through the use of special pipe fittings. The transducers are pre-installed on the flow cell, thus, installation errors are kept to a minimum. In general, wetted transducers provide better accuracy and long-term stability over clamp-on varieties, but usually cost more.

4. Transducer scheme: Single-path vs. Multi-Path

Single-path flowmeters utilize one pair of transducers to form one ultrasonic path to intercept the flow in a pipe. It is suitable for small and medium size pipes. For larger pipe sizes, shorter straight pipe runs and greater accuracy, multi-path transducer installation is a good option. Multi-path flowmeters are traditionally more expensive than a single-path flowmeters, and are often implemented in applications such as custody transfer where accuracy is of paramount important.

Todays handheld ultrasonic flow meters are engineered to deliver fast, non-intrusive flow and BTU measurement across a broad array of pipe sizes and applications for water, waste water, heating, cooling, and other liquid flow applications.

These new meters are completely portable and rely on clamp-on sensors to effectively perform non- intrusive measurements on flow, temperature and heat energy/BTU consumption on pipes ranging from 0.5” to 120” in diameter. Many of these new products range in size from 12 lbs. to as little as 1lb, but provide large data logging storage, rich analog input/output options and comprehensive on-site diagnostic features. “Smart” capabilities via Bluetooth interface together with companion software can provides onsite connectivity to a smart phone or PC for fast data downloading, and detailed data visualization and analysis.

Many of these new portable flow meters like the one mentioned above use transit-time measurement, where the system utilizes a pair of sensors that function as the ultrasonic transmitter and receiver. The sensors are installed on the pipe wall, either clamped on the outside of the pipe or inserted into the pipe at a predetermined distance from one another. The flow meter operates by alternately transmitting and receiving a coded burst of sound energy between the two sensors and measuring the transit time it takes for sound to travel between the two sensors. The difference in the transit time is directly related to the velocity of the liquid in the pipe. The flow rate is then calculated based on the transit-time difference, the geometry of the pipe and the fluid dynamics formula.

The sensors are commonly mounted with the Z-method or V-method. With the Z-method, the two sensors are installed on opposite sides of a pipe. This method offers a shorter sound path, thus, better signal strength, and is often used for large size pipes where signal strength is critical. With the V-method, the two sensors are installed on the same side of a pipe. The sound path is doubled, thus, the measurement accuracy is better. This method is often used for small and medium size pipes.

Portable flow meters are designed to be so compact that you are able to use one hand to hold and operate the meter. The user interface is usually back-lit and easy to read in dark environments. The unique clamp-on fixture design makes the installation easy without needing specialized tools.

Portable ultrasonic flow meter devices are good choices for flow survey, meter verification, pump checking, HVAC balancing, facility management and other demanding flow monitoring applications where measuring the liquid flow from outside of a pipe is preferred . Examples of other suitable applications include:

• Water, including hot water, chilled water, city water, sea water and more.
• Sewage and drainage water with small particle quantity
• Oil, including crude oil, lubricating oil, diesel oil, fuel oil, etc.
• Chemicals, including alcohol, acids and more.
• Solvents
• Beverage and food processors
• HVAC hot and cool water, water/glycol solutions
• Water and waste treatment
• Power plants (nuclear, thermal & hydropower) heat energy boiler feed water
• Metallurgy and mining applications (e.g., acid recovery)
• Marine operation and maintenance
• Pulp and paper
• Pipeline leak detection, inspection, tracking and collection
• Energy measurement and balancing
• Water distribution network monitoring
• Energy consumption supervision and water conservation management

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