When, And Why, Should I Have My Static Meter Calibrated?

Instrument calibration is a big deal in a number of situations. Companies that sell product by weight are (or should be) adamant about keeping their scales calibrated. If they read light, they’re giving unintended discounts. If they’re reading heavy, they’re gouging their customers, and their local Weights & Measures folks take a dim view of that.

A much more serious situation, involving errant instrument readings, took place on a U.S. Navy submarine, USS Greenling (SSN-614) in the spring of 1973. They were conducting tests on a firing a new torpedo that was specifically designed for greater depths. While operating at what they THOUGHT was the ship’s “test depth” – the point at which the designers say the hull can be expected to maintain reliable integrity – the Captain, who was in the Torpedo Room, noticed a pressure gauge on a torpedo tube showed a higher-than-expected reading. They quickly realized the depth gauge in the Control Room was not operating properly, and they were, in fact, alarmingly close to “crush depth” – which is exactly as bad as it sounds. That’s a story every submariner hears early in their career, and it’s the reason that instrument calibration (for ALL systems…not just the depth gauges) is taken QUITE seriously.

In certain industrial and commercial ventures, instrument calibration is critical in that same vein: atmospheric monitoring equipment needs to be accurate or people can be poisoned by toxic gases, or suffocated from lack of oxygen, for example. Other processes aren’t life-threatening, but can have major impacts on production and quality. One of these (and the main subject of this blog) is the ability to measure static charge.

EXAIR’s Model 7905 Digital Static Meter is a handheld instrument that quickly & accurately indicates the static charge that resides on an object’s or material’s surface. If it’s in proper calibration, it can be used to gauge the effectiveness and efficiency of static eliminators, by measuring the static charge before, and after, exposure to the static eliminator product. It can also help to identify the source of static charge by showing specifically where the highest charge resides on an object or piece of material.

EXAIR Model 7905 Digital Static Meter: Because you can’t manage what you don’t measure.

To do so accurately, though, it has to be maintained in good working order. To ensure this, EXAIR Corporation offers calibration service, available at three levels, depending on your specific needs.

  • Level 1 Calibration is performed in accordance with Mil Std 45662A, and is traceable to NIST (National Institute of Standards and Technology) standards. It doesn’t include before/after test data, but does ensure the Static Meter is in good working order and reads accurately. For most typical industrial applications, this is all that’s required.
  • Level 2 Calibration complies with Mil Std 45662A, and is traceable to NIST standards as well. It DOES include before/after test results and lists the laboratory standards used (along with NIST test numbers), which may be called for in compliance with your company’s quality programs.
  • Level 3 Calibration also complies with Mil Std 45662A and is traceable to NIST standards. This level of calibration, however, is performed by an independent laboratory that is accredited for ISO 17025 compliance. The calibration certificate issued satisfies requirements of:
    • Mil Std 45662A
    • ANSI/NCSL Z540-1
    • ISO/IEC Guide 25
    • ISO/IEC 17025

If you don’t recognize any of those requirements, Level 1 Calibration is likely all you need to ensure your Static Meter is functioning properly. A prime example of the need for Level 3 Calibration might be a pharmaceutical goods manufacturer who uses Static Eliminators to ensure cleanliness/sanitation in a packaging evolution, and uses the Static Meter to periodically document the dissipation of the static charge on the packaging material. The before/after results, along with compliance to certain standards, could trigger a safety recall on a potentially unsafe product that presented a very real public health risk.

Prime examples of applications where your Static Meter might need different levels of calibration (from left to right) – an artwork maker using a Gen4 Ion Air Gun can ensure consistency in finished products by periodically having their Static Meter calibrated to Level 1 standards. A playing card manufacturer who uses Gen4 Ionizing Points and sells product to casinos can provide quality documentation to their customers with Static Meters calibrated to Level 2 standards. A pharmaceutical company who uses a Gen4 Ion Air Jet can track quality – and hence public safety – by documenting compliance with the highest levels of regulatory control with Static Meters calibrated to Level 3 standards.

As temperatures drop in the Northern Hemisphere, static charge – and attention to the problems it causes – rises. If you’ve got questions about static elimination, let’s talk.

Russ Bowman, CCASS

Application Engineer
EXAIR Corporation
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Tools Of The Trade: The Rotameter

EXAIR’s Free Efficiency Lab

One of the free services we offer to customers here at EXAIR is our Efficiency Lab. In case you are not familiar here is a brief synopsis. Speak with an Application Engineer about your existing compressed air blowoff/point of use product and that you would like to know how much air it consumes. Fill out the brief survey and send the product you use in to our facility. Let us perform tests on calibrated test equipment to determine the force, flow, and noise level. We will then issue you a report that states what the EXAIR model would best be suited (if applicable) as well as how much compressed air you will be able to save. Order the recommendation and start saving money.

To do these evaluations, we have to have calibrated equipment that is reliable and capable of handling vast range of products we may receive in. For this, we could use a Digital Flowmeter, in some cases that is what has to be done due to large flow rates. For the majority of these though we go old school. We utilize a piece of equipment called a rotameter.

A rotameter pairs nicely with a calibrated pressure gauge as well.

The float can be seen with graduated marks for readings. The taper of the chamber is not easily seen with the naked eye.

This is a device that is designed to measure the flow rate of a fluid within a closed tube. The inside diameter of the tube is varied which causes the float within the meter to raise or lower.  They are calibrated for a specific gas at a given pressure and temperature, most are calibrated for atmospheric conditions, 14.7 psi (1.014 Bar). The meter must be mounted vertically and this is not always best suited for industrial environments.

When testing products the compressed air within the meter is pressurized which means we have to correct the reading for the given pressure, if the temperature is outside of the calibration temp then we must also perform that correction. We do this using a table provided by the manufacturer of the meter or by using the calculations shown to get exact values that may be in between the pressures in the table.

Pressure Correction Table


This will allow us to then multiply the Correction Factor by the meter reading and calculate our corrected flow for the point of use device at a given operating pressure and temperature.

Temperature correction table

Knowing where the values that are measured and calculated come from add validity to the reports and understanding all of the variables that go into reading like this helps to better validate the cost savings that can be seen.

In a pinch, for a field estimation, we can also use these Correction Factors and determine an approximate consumption rate of a device that has been measured at a pressure such as our cataloged 80 psig (5.5 Bar). This can often be done on the fly to help determine the flowrates currently on a system. This can be helpful when troubleshooting, giving estimated simple ROIs, and help justify results and reasons for future purchases of engineered solutions.

If you want to discuss the Efficiency Lab or any of the math behind our calculations, contact any Application Engineer, we can all help out.

Brian Farno
Application Engineer

Calibration – Keep Your Meters True

EXAIR offers meters to measure the level of physical parameters such as sound and static. Each meter has sensitive electrical circuitry and a periodic calibration is recommended to ensure the meter readings are tried and true.

The model 9104 Digital Sound Level Meter is an easy to use instrument that measures and monitors the sound level pressure in a wide variety of industrial environments. The source of loud noises can be quickly identified so that corrective measures can be taken to keep sound levels at or below OSHA maximum allowable exposure limits.

The sound meter comes from the factory with an NIST (National Institute of Standards and Technology) certificate of accuracy and calibration.  As a good practice, EXAIR recommends a yearly calibration of the instrument, and we offer a service that calibrates the unit to the same NIST standards and provide a written report of the calibration.

The model 7905 Static Meter allows easy one-hand static measurements.  It is useful in both locating sources of high static charge and checking the reduction of static after treatment with an EXAIR Static Elimination product.  The unit is sensitive and responsive, and indicates the the surface polarity of objects up to +/- 20 kV when measured from 1″ away.

It is also recommended that the Static Meter be calibrated on a yearly basis.  EXAIR offers (3) levels of calibration service.  The first two provide calibration in accordance with MIL Standards using accepted procedures and standards traceable to NIST.  The third calibration service conforms to the same Mil Standard, as well as ISO/IEC standards.

Annual calibration service of your EXAIR Digital Sound and Static Meter, along with proper care and storage, will keep your meter performing tried and true for many years, providing accurate and useful measurements.

To initiate a calibration service, give us a call and an Application Engineer will issue an Returned Good number, and provide instructions on how to ship the meter to EXAIR.

If you have questions regarding calibration services for your meters or would like to talk about any EXAIR Intelligent Compressed Air® Product, feel free to contact EXAIR and myself or one of our Application Engineers can help you determine the best solution.

Brian Bergmann
Application Engineer

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