How to Choose a Tachometer and Sensor

Answering the following questions will help you to identify the tachometer and compatible sensor that is best suited for your application.

1.) Does your tachometer application require a portable handheld or panel/bench top model?

2.) What RPM range do you need to measure?

3.) In addition to a tachometer, are totalizer/counter or timer/stopwatch measurements required?

• PLT200 Pocket Laser Tachometer is a Tachometer, Totalizer/Counter, Timer/Stopwatch.
• ACT‐3X is a Tachometer, Totalizer/Counter.

4.) Does the application require a remote optical sensor (handheld or mounted) in a remote location?

• PLT‐200 can be used with a ROS‐P, ROLS‐P, MT‐190‐P, IRS‐P sensor with 8 or 25‐foot cable lengths.
• The ACT Series used with Remote Optical Sensor (ROS‐W) has a standard cable length of 8 feet with up to 400 feet available. Additional bulk cable is priced at $1.00/foot over standard 8‐foot cable length for sensor.

NOTE: W = Tinned Wires, and P = 1/8″ (3.5mm) Phone plug. P-connectors plug into a tachometer or strobe.

Optical tachometers and sensors will shoot/operate through glass, plastic and wire mesh protective screens.

5.) Can you shut down the machine to be measured/analyzed so that you can attach a 1/2 inch piece of reflective tape for measuring?

If yes, use a non‐contact optical tachometer like the Pocket Tach PT99 or Pocket Laser Tachometer PLT200. However, if you cannot safely stop the machinery, use a contact tachometer. The PLT200 Kit includes the Remote Contact Assembly which makes the PLT200 a contact tachometer. In addition, our Nova-Pro^® Stroboscopes/Tachometers are two in one instruments that measure RPM, stop motion, and much more.

• PT99 Pocket Tachometer operates up to 36 inches + 45° from reflective tape.
• PLT200 Pocket Laser Tachometer operates up to 25 feet from reflective tape and +/‐ 70 degrees.
• ACT Series with a Remote Optical Sensor operates up to 36 inches + 45° from reflective tape.
• ACT Series with a Remote Optical Laser Sensor operates up to 25 feet from reflective tape.
• ACT Series with a Smart Laser Sensor operates up to 65 feet + 70° from reflective tape.

7.) Does the application require a contact tachometer to measure RPM or linear speeds of moving machinery such as a conveyor belt or elevator speed? Do you require measurement in inches per minute, feet per minute, or meters per minute?

• PLT200 Kit includes the Remote Contact Assembly. With the RCA’s tips and wheels, the PLT200 becomes a contact tachometer.
• PLT200 Kit will measure all English or metric linear unit rates and is the best value for contact/non‐contact linear speeds or RPM.

8.) Does the operating environment prevent using a reflective tape target?

Maximum temperature for continuous operation using Monarch Instrument’s T-5 Reflective Tape is 175 °F ( 79.4 °C). If dirt, oil or water gets on optics or target or speed exceeds 60,000 RPM, then the Reflective Tape could come off. Try to use a IRS‐P Infrared Sensor (painted target) or magnetic or proximity sensor from a bolt head, gear teeth or drill and tap a ¼ ‐20 bolt into the coupling.

ACT models can be used with Magnetic Sensor (MT‐190W), Magnetic Sensor with Amplifier (MT‐190W), Proximity Sensor (P5‐11), Infrared Sensor (IRS‐W), Remote Optical Laser Sensor (ROLS‐W) and Smart Laser Sensor (SLS‐115/230). The gap for the Magnetic Sensor must be .005 inches max to gear teeth. The MT‐190W Magnetic Trigger Sensor with Amplifier allows an increased gap up to .250 inches from a ferrous target like bolts or teeth.

The P5-11 Proximity Sensor is mounted up to a .200 inch operating gap from a metallic target usually a bolt head, keyway or ANY 1/ 2 inch square area protruding on the rotating device. Operates up to 250 feet from the tachometer. The P5‐11 is smaller and easier to install than a magnetic sensors.

The PLT200 or ACT Series used with an Infrared Sensor can be used on targets where tape cannot be used. Must mark surface with white/black contrast colored target such as wax crayon, paint or black felt tip marker pen. The Infrared Sensor’s converging .5‐inch beam could also be “broken” by the rotating device to trigger an input to tachometer. For example you can shoot infrared beam through gear teeth.

9.) Do you require additional output options from the tachometer?

NOTE: ACT‐3X has all output options available and INCLUDES NIST (National Institute of Standards and Technology) Certificate of Calibration with no extra charge. Best value for customer’s dollar!

10.) What input power is available to power the tachometer?

Select the proper supply power for your ACT Series using the model number matrix or use a battery-powered PT99, or a PLT200 when supply power is not available.

11.) What accessories/options do you need for your Monarch Instrument tachometer?

The PLT200 is offered as a standalone device or in kit form, which includes a latching carrying case, roll of T‐5 Reflective Tape and a Remote Contact Assembly (RCA) for contact measurements. Don’t forget to order sensors or extra reflective tape!

12.) Do you require a NIST Certificate of Calibration for your Monarch Instrument device?

The PLT200 Pocket Laser Tachometer, SLS Sensor and ACT‐3X Panel Tachometer include a NIST Certificate of Calibration at no additional charge. All other digital instruments can be supplied with a NIST Traceable Calibration Certificate at an additional charge. The initial certificate is good for 12 –18 months.