In a recent post, I said that one of the important features in a calibrator is flexibility or versatility. You might say it’s the Swiss Army knife (a registered trademark of Wenger S.A. and Victorinox A.G.) effect. I know that sometimes mashing things together makes a whole that’s a lot less than the sum of its parts, but…

For calibrators that’s not the case. In fact, because they are often the most highly engineered products a company offers, multi-function calibrators may offer the best overall performance in a company’s line. There don’t really need to be too many tradeoffs.

Sure, the multi-function calibrator is likely to be larger than its single function relatives and certainly a bit more complex, but having every tool you need everytime you need it is worth it for many. Our MC-1200 has the capabiltiy of a loop calibrator (and just as easy to use), a high performance temperature calibrator (just about every T/C and RTD curve you can think of), a wide ranging pressure calibrator (29 ranges and styles of Beta pressure modules), DC voltage and frequency (with pulse train output).

That’s what I mean about versatile.

Valve Location

I’ve been posting a lot about the BetaGauge 330 lately because we’ve had a lot of new developments for it. With the revolutionary built-in battery operated test pump, it has become our flagship product. So, we spend a lot of time trying to make it even better.

The good news/bad news is that the strength of the 330 (built-in pump) is also its Achilles heel. Contamination of the pump valves will make it leak and/or not work. We considered that in the initial design and made those valves easy for the customer to access (picture at left) and clean (video at YouTube).

That, by itself, might be good enough for some.

However, we want to go even further and stop a potential problem before it even starts. In this case, the potential problem is liquid being sucked into the pump mechanism from the device under test. When this happens, you’re looking at more than just cleaning the valves. It’s time for a full rebuild, which is time consuming and more difficult.

LDT-500 Liquid/Dirt Trap

So, we’ve designed and are building a liquid/dirt trap accessory for the BetaGauge 330, The LDT-500. Beginning this month, all 330s will ship with this device as standard. It mounts on the calibrator’s pressure port between the calibrator and any potential contaminant. With its clear body, it’s easy for the technician to see when a problem might be occuring and prevent it. The LDT-500 will also be available separately for users who already own a BetaGauge 330 and want to protect it.

The design of the LDT-500 is pretty clever, too. It’s virtually tooless as it screws into the calibrator port and seals with an o-ring. No pipe sealant tape required. The open process port is Martel’s unique NPT/BSP thread for universal use. Cleaning of the LDT is tool free, too. The end caps unscrew by hand, making it easy to clean out. If needed, replacement o-ring seals are available as a maintenance kit.

We’re working on even more improvements for the BetaGauge 330, so keep in touch.

BetaGauge330

In June, we started shipping the BetaGauge 330 with available absolute pressure internal sensors. The 330 is now available with a 30 PSIA (2 barA) or a 150 PSIA (10 barA) internal sensor.

The new ranges offer the same ±0.025% of full scale accuracy (6 month specification) as the previously offered gauge ranges (30, 150 & 300 PSI).

Some of the other useful features of the 330 are

• built-in loop calibrator (input and output
• large multi-variable display
• 24 VDC instrument power supply
• automatic pressure switch test
• available gas custody meter calibration kit
• 17 engineering unit displays
• external pressure module compatible

For a surprisingly low cost in a surprisingly small and lightweight package, the BetaGauge 330 has a lot to offer.

Martel calibrator user Bruce Schmeck is quoted in the March, 2010, issue of Control Magazine saying, “We use field calibrators…for all kinds of biochemical batches to monitor and verify temperature, pressure, flow and agitation.”

In the same article, one of our competitors surveyed users and unsurprisingly discovered that a lot of them aren’t calibrating the instruments in their plants.

The article goes on to point out that many users have been sold a bill of goods about their instrumentation from the makers of that instrumentation. To wit,”our digital instruments don’t drift, so they don’t need to be calibrated.”

BetaGauge 321A Dual Range Pressure Calibrator

Mr. Schmeck also explained in this article that it isn’t the digital part of new instruments that drifts; it’s the part where the rubber meets the road, so to speak. He cites the example of the metal diaphragm in a pressure transmitter. The metal will age and its response characteristics will change over time. The ONLY way to fix that is to use a traceable field calibrator to inject a known valid signal.

To sum it up, here’s another quote from Bruce Schmeck that I like, “Most calibrators need to be re-calibrated once per year.” I love it.

Did you know that the accuracy and validity of natural gas custody transfer metering is covered under the US Sarbanes Oxley law?

I didn’t either until I read this informative post by Jim Cahill over at the Emerson Process Experts blog.

Here’s my short take on what’s required to do a professional job at custody transfer metering for many industries.

• Proper design and installation of metering equipment, which includes selecting the right equipment in the first place. This is a very competitive market and there’s plenty of great hardware available. So, this really boils down to quality installation design and implementation.
• Routine and regular verification of the performance of the system. This is where Martel comes in the a range of useful calibration products such as the BetaGauge 321A. Our calibrators have the performance, reliability and features needed to do a great job of calibrating gas custody transfer systems.
• Technicians who are professionally trained professionals. This may be the hardest piece of the puzzle to fit in. Finding, keeping and motivating quality personnel is a major challenge for corporations world-wide.

It’s ironic that one of the events that instigated the Sarbanes Oxley Act was the implosion of Enron Corporation, a company that started out in the natural gas energy business.

BetaGauge 321 Dual Range Pressure Calibrator

I’m not referring to an old time game show or parlor game as they used to be known. My question is, “Can you trust your vendor’s calibration certificate?”

There are a few indicators you can use.

1. What kind of reputation does the company have in the industry? You know, how long have they been around and do other customers respect their products and service? There are a number of industry surveys and reports that can help with this if you don’t feel comfortable making your own assessment.
2. Is the certificate traceable to NIST or other national standards body? This may seem obvious, but read the statement see if it makes sense to you. Are there unsupported assertions about things like TUR (Total Uncertainty Ratio) or Guide 25 approval?
3. Are the standards used properly identified and are they appropriate for the task at hand? For example, if a specification is % of reading, but the standard’s specification is % of scale, there’s a significant mismatch. You may also need to check to see if the standard has been properly maintained with acceptable calibration intevals.
4. Does the certificate include data that is clearly presented and meaningful? Are there sufficient data points to assess performance?
5. If possible, check the calibration at intervals different from the cardinal points on the certificate. Even a bump check can provide revealing information.

Finally, is the calibration accredited under an international standard (ISO 17025) or do you need such an accredited calibration. Even if it’s offered as an option, the vendor must have a pretty good idea that the normal calibration is valid.

The current issue of Control Magazine (digital edition here) has a whole page of links to worthwhile calibration resources from some of the big players in the industry.

Most of them are white papers, but one is another web site with a “ton” of great links to other resources.

If you need to learn or know more about important calibration issues, you should have a look.

Temperature sensor calibration is not something industrial technicians often deal with. At most, they’re going to tweak a transmitter or some receiver device to reduce or eliminate the inherent error in the sensor. Unfortunately, that can only be done at a single temperature.

Martel 3001

It’s a different story for higher end devices like the Martel 3001 Bench Calibrator or even our hand held MC-1200 and DMC-1400 multifunction calibrators. For them you can enter constants for your temperature sensor so it is matched to the calibrator across the entire measurement range. This makes the calibrator into a very accurate thermometer.

This begs 2 questions. One, how do I get those contants to enter into the calibrator, and, two, what’s the point of doing this?

First, let’s make one point clear. The probes we’re talking about are resistance temperature detectors (RTDs), sometimes also called PRTs or SPRTs. The Hart Scientific guys over at Fluke have a very nice white paper about how to take a probe more or less off the shelf and get the constants for it. However, you normally get the constants from the probe vendor. These kind of probes cost more as you have to pay for the data.

The 3001 can use either Calendar-Van Dusen constants or ITS-90 data for curve fitting. The hand held calibrators only work with the Calendar-Van Dusen constants.

Other than for checking the temperature of something what’s the point of this? Well, that is the point and the most useful and common application is to use the calibrator/probe combination with a dry well temperature calibrator to improve its overall performance in testing and calibrating temperature loops.

Sometimes we don’t do a good enough job letting people know what they are getting for their money.

As a rule, I would say that we give people a working product with everything that’s needed to put it to work right away. We even include BATTERIES.

T-140 Kit Ship Sheet

To see what we really ship with a product, I look at what we call the Ship Sheet. This is the guide for the shipping department to make sure that nothing is forgotten or left out of the box that’s supposed to be there.

You can see an example to the right. This is the ship sheet for a low range T-140 pressure calibrator kit. Here’s what’s in the box:

1. The calibrator (T-140)
2. The instruction manual
3. NIST calibration certificate
4. Hard plastic carrying case with foam insert
5. MECP100 pneumatic hand pump
6. Labels for the pump
7. Various fittings
8. Tubing cut to a 3′/1m length
9. Teflon tape
10. Shipping bag for the calibrator
11. Product registration postcard
12. Thank you card
13. Label for the carrying case

So, everything you normally need is there.

Q. Can the BetaGauge 330 be field recalibrated?

A. Yes. The BetaGauge 330 is calibrated through the serial port like many Martel calibrators. Other than a computer with a terminal emulation program (we normally recommend HyperTerminal), a LEM232 serial communications cable is needed along with a URA-1 RTD adapter. Both of these can be purchased through your Martel distributor.

You will also need some adequate standards for pressure, current (mA), voltage and resistance.

The procedure is available from the factory or your local Martel distributor.