Ultrasonic Flow Meters
Presented by
Brent Baird
© Instruments Direct 2014

Ultrasonic Flow Meters
Presentation Outline:
• Introduction
• Why do you need energy metering?
• Hydronic System Energy Metering applications
• Noncontact Ultrasonic technology
• Noncontact Temperature monitoring
• Application of noncontact energy monitoring applications
• Economics

Ultrasonic Flow Meters

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Office Building A
$94,658
Office Building B
$47,905
$46,753

Ultrasonic Flow Meters
Each building requires 470 tons of cooling; accomplished by way of:
(2) air-cooled helical-rotary chillers piped in parallel
(1) Pump per Chiller
System Flow
Pumping
Energy
Consumed
Monthly
Annual
Operating
Costs
Office Building
A
Constant Primary,
Constant Secondary
52,588 kWh $94,658
Office Building
B
Variable Primary,
Variable, Secondary
(VPF)
*assuming $0.15 per kWh
26,614 kWh $47,905

Ultrasonic Flow Meters
• How do you determine the efficiencies of your current system?
• Discover Process
• Use a reference meter to establish a baseline and map out your sources:
-Hot and Chilled water
-Temperature (Differential) BTU

Ultrasonic Flow Meters
What is Hydronic System Energy Metering?
A hydronic energy meter, also referred to as a BTU meter or heat meter. It measures heat energy generated by a source or transferred to a load depending on heating or cooling demands.
Energy Measurement unit is called Btu (British thermal unit)
• Btu = The amount of heat energy it takes to raise the temperature of one pound of water by one degree Fahrenheit, at sea level.

Ultrasonic Flow Meters
• BTU/hr = flow rate in GPM (Δ Temp) 500
500 = the “fluid factor” this is based on water as the heat transfer fluid. The fluid factor is obtained by using the weight of a gallon of water (8.33 lbs.) multiplied by the specific heat of the water (1.0) multiplied by 60 (minutes). This comes out to 499.8 when using water.
GPM*(abs(temp supply-temp return)*ROUND(((1-(((((temp supply+temp Return)/2)-
32)/1.8)+288.9414)/(508929.2*(((((temp supply+temp Return)/2)-32)/1.8)+68.12963))*(((((temp supply+temp Return)/2)-32)/1.8)-3.9863)^2)*8.34540445),3)*1)=BTU/min

How it works:
Ultrasonic Flow Meters

Ultrasonic Flow Meters
What have we learned so far:
-We need to monitor our energy system to optimize performance.
+ Flow – Supply
+ Temperature – Supply
+ Temperature – Return

Main Building
A
Annex Building
B
Ultrasonic Flow Meters
Building / Campus Mapping:
Annex Building
C
• In calculating energy use, each building is unique.
• Address temperature loss or gain when transferring CHWS, CHWR.
• Meter all flows and temperatures, you cant afford not too…

Ultrasonic Flow Meters
Key Issue(s):
-Too many application assumptions are being made
-Installations not per specifications
-Accuracies of metering instruments
-Poor or inaccurate data collection.

Ultrasonic Flow Meters
• For chilled water applications, where the sensor supplies only volume information to a Building Automation System (BAS), each percentage error the flow meter is off will have a direct impact on the Btu calculation.
• Flow meter technologies come with wide accuracy statements.
• For instance, if one flow sensor is advertised with accuracies of
1% of Reading while another is 1% Full Scale, the energy calculation can be off by 4% when flows are run at 25% of full range.

Ultrasonic Flow Meters
Example: On an 8” Chilled Water line; a 1% of Reading Ultrasonic and a 1% FS Impeller are installed. Both have max working flow rates of 0-
4000 GPM with an application design flow of 1000 GPM.
The ultrasonic meter will offer readings of 990-1010 GPM in order to meet its advertised +/-1% of readings.
The impeller meter will offer readings of 960-1040 GPM in order to satisfy its +/-1% of Full Scale readings.
Assuming a delta-T of 15 º F, the designed flow of 1000 GPM, and a water constant of 499: Q(Btu/hr) = (GPM)(499)(delta-T)
True Energy Value = 7485 MBtu/Hr
Ultrasonic = 7410 – 7560 MBtu/Hr, or +/- 1%
Impeller = 7186 – 7784 MBtu/Hr, or +/- 4%

Ultrasonic Flow Meters
Example:
• For chilled water applications, temperature sensor accuracy relative to each other becomes significant since the temperature differences can be small (<10 ° F).
• For instance, if one sensor reads 1 ° F high while the other is 1 ° F low , the energy calculation can be off by 20%.
• A selfcontained “Btu” meter is recommended as opposed to using separate flow and temperature sensors because the accuracy is generally better (matched sensors) and data collection is simpler, particularly if energy is being metered for revenue purposes.

Ultrasonic Flow Meters
When selecting technology, you should consider:
Pipe considerations – Include pipe size and material, layout, and straight pipe runs available for flow sensor installation.
Flow rate –Flow sensors must be sized to accommodate any balancing configuration or valve position.
System temperature – Flow and temperature sensors are designed especially for chilled or hot water systems. Example: thermistors are fine for chilled water, but RTD’s are a better selection for hot water systems.
Accuracy – Accuracy and repeatability help determine how precise your energy measurements will be. Some applications leverage tighter accuracy and repeatability tolerances to maintain tighter controls on hydronic system performance.
Service considerations – For new installations, direct insertion of sensors is usually possible.
However, when retro-fitting a system, often pipes cannot be drained requiring a wet tap.
Optional display – Depending on owner requirements, local displays of flow, temperature, energy rate, and/or energy totals may be required.
Optional connectivity – Data logging and Building Automation System (BAS) networks, in addition to simple pulse and analog signals, include many different network protocols

Ultrasonic Flow Meters
Energy Management is Key
• Optimizing usage/minimizing operating costs
– Energy distribution
• Measuring consumption
– System monitoring
• Cost allocation
– Energy sub-metering
• Measurement and Verification is an essential part of every energy efficiency facility program
• Federal and state agencies encourage investment in energy-saving technology

Ultrasonic Flow Meters
Submetering - involves the installation of equipment to measure, monitor, bill or control your process of your water, sewer, gas and electric use. Because submetering raises facility operation awareness, users work harder to conserve, thereby reducing overall consumption dramatically.
Discovery-(Portable) Metering – Insertion meters can be very time consuming and expensive. Clamp-on survey meters are more practical. Ideal for spot check or extended study. Justification to add submetering or retrofit your system.

Ultrasonic Flow Meters

Ultrasonic Flow Meters
The Doppler meter continuously transmits high frequency sound that travels through the pipe wall and into the flowing liquid.
Sound is reflected back to the sensor from solids or bubbles in the fluid. If the fluid is in motion, the echoes return at an altered frequency proportionate to flow velocity.
Doppler flow meters continuously measure this frequency shift to calculate flow.

Ultrasonic Flow Meters
B
A

Ultrasonic Flow Meters
THE SOUND'S TIME OF FLIGHT IS
ACCURATELY MEASURED IN BOTH
DIRECTIONS AND THE DIFFERENCE IN TIME
OF FLIGHT CALCULATED.

Ultrasonic Flow Meters

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Ultrasonic Flow Meters
APPLICATIONS:
* Water Monitoring
* Energy Management
* HVAC
* Test & Balance
* Chillers
* Cooling Towers
* Boilers
* And More……..

Ultrasonic Flow Meters
Clamp-on, Portable
– Uses ultrasound waves to measure flow
– Non-invasive
– No need to shut down system
– Rental & Purchase
• Applications
– Relatively clean cold or hot fluids, pipes must be full
– No maintenance costs

Ultrasonic Flow Meters
Clamp-on, Fixed
– Uses ultrasound waves to measure flow
– Non-invasive
– No need to shut down system
– Economical Price
• Applications
– Relatively clean cold or hot fluids, pipes must be full
– No maintenance costs

Ultrasonic Flow Meters
Flow - Temperature Monitoring

Ultrasonic Flow Meters
Resistance temperature detectors or RTD’s as they are more commonly known, are another common way to measure temperature.
To use an RTD, a small voltage is passed through the element and then measured. The resistance of the element reduces the voltage and this voltage drop can be converted into a temperature measurement.
With most RTD’s, the higher the temperature, the higher the resistance.
5(w) + 1000 + 5(r) = 1010 – (5(w) + 5 (r)) = 1000

Ultrasonic Flow Meters
The 3-wire circuit does allow for compensation of lead wire resistance, which is normally done by the measuring instrument.
The instrument measures the resistance between the red and the white leads and then subtracts the resistance between the two reds.
5(w) + 1000 + 5(r) = 1010 – (5(w) + 5 (r)) = 1000

Ultrasonic Flow Meters
Temperature – Flow Monitoring

Ultrasonic Flow Meters
Temperature – Flow Monitoring

Ultrasonic Flow Meters
Location.. Location… Location….
• Mount the RTD – temperature sensors in the identical location on the supply and the return (metal) pipes.
• Failure to-do so will result in temperature differentials that can effect your performance of the BTU calculations

Ultrasonic Flow Meters
• Discover process.
• Spot check flows
• Water usage study
• Energy usage study
• Balancing Hydronic system
• Economics

Ultrasonic Flow Meters
Energy monitoring & control by monitoring BTU
• Flow and temperature
• Domestic hot & cold water
• Air conditioning / Heater
• Communications
- 4/20mA
- Modbus
- Ethernet
- BACnet MSTP
- BACnet/IP
Modbus TCP/IP…..
• Economics

Ultrasonic Flow Meters

Summary:
Ultrasonic Flow Meters
• We all live in a bubble and need to control our environment
• Energy monitoring can enhance your facilities efficiencies
• A discovery process is necessary to establish a baseline
• There are different ultrasonic technologies
• Install submetering correctly for accurate continual data collection and operations of your facility.
• Define communications for your submetering
• Validate your ROI on any system upgrades.

Brent Baird
CEO / Application Engr / Technical Speaker
Instruments Direct
Ph 1(888)722-5543 bbaird@instrumentsdirect.com
© Instruments Direct 2014

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© Instruments Direct 2014