Efficient Plant July 2018 - 33
Choose the Correct
Answering eight questions on how and where an accelerometer is to be used
simplifies the selection process. Photo: IMI Sensors
1. WHAT TYPE OF DATA IS REQUIRED?
Raw or overall data: An accelerometer's VAC signal is a dynamic
signal on which frequency analysis can be performed while a vibration transmitter's continuous 4-to-20-mA signal of overall values
can connect directly with PLC, DCS, and SCADA systems.
Acceleration, velocity, or displacement: The appropriate measurement range depends on the frequency of the measured vibration.
+ displacement: 0 to 10 Hz
+ velocity: 10 to 2,000 Hz
+ acceleration: greater than 2,000 Hz.
2. WHAT IS THE VIBRATION AMPLITUDE?
The maximum amplitude of the measured vibration will determine
the sensor's measurement range.
+ common accelerometer ranges: 10, 50, 100, and 500 g
+ common vibration-transmitter ranges: 0 to 1 and 0 to 2 ips;
0 to 5 and 0 to 10 g
3. WHAT IS THE VIBRATION FREQUENCY?
Low-frequency response: Most industrial sensors will have a limit
near 0.2 Hz.
High-frequency response: Sensors have a resonant frequency at
which the signal is amplified, leading to sensitivity changes and
possible saturation. To combat saturation, most industrial accelerometers have single- or double-pole RC filters.
4. WHAT IS THE TEMPERATURE OF THE
Determine the highest and lowest temperatures to which the sensor
will be subjected.
+ -65 F to 250 F: Most general-purpose industrial sensors with
integral electronics can operate in this range.
+ 250 F to 325 F: High-temperature sensors with special integral
SELECTING ACCELEROMETERS for specific applications need
not be difficult. Meredith Christman of IMI Sensors, Depew, NY
(pcb.com), says the process basically involves answering eight questions.
- Jane Alexander, Managing Editor
electronics are available since higher temperatures can harm
built-in electronics of general-purpose units.
+ >325 F: Charge-mode designs without built-in electronics are
5. WILL THE UNIT BE SUBMERSED IN LIQUID?
Depths <1,700 ft.: Sensors with integral cables can be permanently
submersed without additional testing.
Depths >1,700 ft.: Sensor should be pressure tested for one hour.
6. WILL THE UNIT BE EXPOSED TO CHEMICALS?
Sensors: Industrial designs feature corrosion-resistant
Cables/connectors: Check a chemical-compatibility chart. With corrosive chemicals, use PTFE cable with non-corrosive connectors.
7. DO YOU WANT PRECISION OR LOW COST?
Calibration: Precision sensors receive a full calibration. Low-cost
designs receive single-point calibration.
Tolerances: Precision sensors have tighter tolerances on specifications such as sensitivity, i.e., sensitivity tolerance of ±5% versus
±10% for low-cost designs.
8. ARE SPECIAL APPROVALS REQUIRED?
Most industrial sensors can be certified as intrinsically safe for potentially explosive areas. Compare the type of approval needed with
a sensor's published approvals to ensure it meets your particular
Meredith Christman is a product-marketing manager with IMI
Sensors, a division of PCB Piezotronics, Depew, NY. Learn more about a
range of condition-monitoring solutions at pcb.com.
Table of Contents for the Digital Edition of Efficient Plant July 2018
Find Gold In Sustainable Manufacturing
Troubleshoot Control Systems Effectively
Automation Accelerates Beer Production
Lubed Chains Live Long Lives
SAP: Use These Tools For PM Compliance
Protect Your Site From Cyber Attacks
Build The Value Of Your CM Program
Choose The Correct Acclerometer
On The Floor
Intelligent Design Process Delivers For Substation
Old Compressor Gets New Lease On Life
Efficient Plant July 2018 - Cover1
Efficient Plant July 2018 - Cover2
Efficient Plant July 2018 - 1
Efficient Plant July 2018 - 2
Efficient Plant July 2018 - 3
Efficient Plant July 2018 - 4
Efficient Plant July 2018 - 5
Efficient Plant July 2018 - Editorial
Efficient Plant July 2018 - 7
Efficient Plant July 2018 - Implementations
Efficient Plant July 2018 - 9
Efficient Plant July 2018 - Find Gold In Sustainable Manufacturing
Efficient Plant July 2018 - 11
Efficient Plant July 2018 - 12
Efficient Plant July 2018 - 13
Efficient Plant July 2018 - 14
Efficient Plant July 2018 - 15
Efficient Plant July 2018 - 16
Efficient Plant July 2018 - 17
Efficient Plant July 2018 - Troubleshoot Control Systems Effectively
Efficient Plant July 2018 - 19
Efficient Plant July 2018 - 20
Efficient Plant July 2018 - 21
Efficient Plant July 2018 - Automation Accelerates Beer Production
Efficient Plant July 2018 - 23
Efficient Plant July 2018 - 24
Efficient Plant July 2018 - 25
Efficient Plant July 2018 - 26
Efficient Plant July 2018 - Lubed Chains Live Long Lives
Efficient Plant July 2018 - 28
Efficient Plant July 2018 - 29
Efficient Plant July 2018 - SAP: Use These Tools For PM Compliance
Efficient Plant July 2018 - Protect Your Site From Cyber Attacks
Efficient Plant July 2018 - Build The Value Of Your CM Program
Efficient Plant July 2018 - Choose The Correct Acclerometer
Efficient Plant July 2018 - On The Floor
Efficient Plant July 2018 - 35
Efficient Plant July 2018 - Solution Focus
Efficient Plant July 2018 - 37
Efficient Plant July 2018 - 38
Efficient Plant July 2018 - 39
Efficient Plant July 2018 - Old Compressor Gets New Lease On Life
Efficient Plant July 2018 - 41
Efficient Plant July 2018 - Products
Efficient Plant July 2018 - 43
Efficient Plant July 2018 - 44
Efficient Plant July 2018 - 45
Efficient Plant July 2018 - Index
Efficient Plant July 2018 - Showcase
Efficient Plant July 2018 - Seeking Reliability
Efficient Plant July 2018 - Cover3
Efficient Plant July 2018 - Cover4