Most of our calibrators are designed to use standard replaceable Alkaline batteries. You know, the ones you can buy at the corner store. That’s a good choice because of the relatively high power density and mostly flat discharge curve of these cells. They start out with a high terminal voltage (1.5 V  or more). A really strong point for these batteries is the long shelf life. If you don’t use your calibrator much, that would be a good reason to use Alkalines. New ones typically have a shelf life of 3 years or more.

On the flip side, if you are a heavy calibrator user, rechargeable batteries, especially very high energy density Nickel Metal Hydride batteries would be a good choice. What is meant by high energy density? Energy in the battery world is measured in Amp hours. For small batteries, it’s most commonly milliAmp hours.

AA Alkaline batteries are typically rated at 2000 mAH. They’re small so they have a high density. Even inexpensive Nickel Metal Hydride batteries now come with 2700 mAH ratings. They have another plus. Although the battery terminal voltage for NiMH batteries starts out at 1.2V, the discharge cycle is extremely flat and the internal resistance is lower. They work right up to the end, so to speak.

You may get as much as 40% more usage from the NiMHs than the Alkalines when they are fully charged. But, that’s the rub. The shelf like of rechargeable batteries is not good in 2 ways. One, they need to be charged regularly, and, two, they will lose their charge when not being used. Infrequent users may find their rechargeable batteries are dead just when they want to use their calibrators.

Here are the tips in short form.

1. If you use your calibrator everyday and use it a lot, consider switching to rechargeable batteries. They are reliable and efficient and you’ll help save the planet. You will recharge your calibrator every night.
2. If you have poor access to replaceable Alkaline batteries, also consider changing to rechargeable batteries. Just remember to keep them charged.
3. If you don’t use your calibrator much, stick with the Alkaline batteries. They’ll be ready when you are unless you have situation 2 above. In this case, if you do use rechargeable batteries, just remember to charge them once a week or at least a couple of times a month.

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.

We (people actually in the calibration industry) often hear things being called calibrators that obviously aren’t. A great example is the Emerson HART(tm) communicator. No offense intended, but these types of devices aren’t calibrators, they are electronic “screwdrivers” that enable a technician or engineer to adjust the calibration of a device.

Here are my defining points for a calibrator.

1. Can make a precision measurement or generate a precision signal (i.e., analog, not digital). Or BOTH.
2. Has a calibration that is traceable to national standards.
3. Has a known accuracy or degree of calibration uncertainty.

There is a lot that could be added to this list, of course; things such as conformance to international standards, EX ratings…

Another little list of mine is this list of characteristics that make up a good calibrator.

• Accuracy
• Flexibility or versatility
• Ease of use
• Reliability
• Ergonomics (small, lightweight, easy to read display, etc.)
• Value

To me, a great example of all of the above is the Martel BETA MC-1200 Multi-function Calibrator. It’s got a long list of features, top knotch performance and is a great deal for the money. Total cost of ownership is good because all they ever require is annual recalibration which anyone with a computer and adequate standards can do.

We have updated the very popular and powerful BetaGauge 311 and BetaGauge 321 Advanced Pressure Calibrators. The new models are the single range BetaGauge 311A and dual range BetaGauge 321A. What we didn’t change are the great performance and ease of use we already had.

Here are the new features:

• Super rugged “Power-Tool-Tough” housing. We’re using the same plastic used in high end cordless drills and the like to make the BetaGauge 311A/321A virtually indestructible.
• Custom engineering units. If you don’t like any of the 19 built-in engineering units, you can configure up to 2 additional units. If you give us the factor information and unit name at the time of order, we’ll even put it in for you at no extra cost.
• Enhanced measurement stability. We updated the circuit design on the pressure sensors with our latest technology to provide better all around performance over a wide range of temperatures and with less long term drift.
• User selectable resolution. Sometimes, there’s too much resolution for the intended application. Those extra digits can make the job harder not better. So, you can reduce the displayed resolution by a single digit in any application.
• More compatible ranges. With 29 possible ranges, we let the user choose what’s right for them. Now, we’ve made the ranges more compatible with long time industry practice by providing compound measurement on most ranges below 500 PSI (35 Bar).

See our web site for more details. The new calibrators are available NOW!

At the upcoming ISA EXPO 2009 in Houston, Texas, we’re introducing a new software package for data logging on the BetaGauge PI or BetaGauge PIR digital test gauges. The dates for the EXPO are October 6 through 8. Our booth number is 2316. Come see us.

BetaGauge PI Reference Class with MECP500 Pump

Our customers already know how rugged, reliable and useful these gauges are. Now, they’re even more useful. Detailed information about the software and its capabilities can be found here.

Here are some highlights:

 • Ability to log both pressure and ambient temperature (UNIQUE).
 • Up to 8500 data points logged.
 • Data stored in industry standard spread sheet formats (CSV or Excel).
 • Multiple log runs stored in gauge
 • Demand (ad hoc) or Download (computer) configured log runs

Applications supported include:

 • Hydrostatic pressure testing
 • Leak detection
 • Transient pressure spike detection
 • Well head monitoring

You can ask your local Martel Distributor for a quote.

Sometimes our customers actually have problems with our products. When they do, they need help fast. We take pride in our level of customer service in that we apply the resources needed to deal with an issue promptly. Here’s another unsolicited response from a now happy customer.

“Thanks for the speedy assistance.  I don’t usually see that kind of response to a problem.” – Mike

And here’s another,

“We normally get great service from Martel and that’s what keep’s us coming back.” – Dan

Not only is our response fast, but we also have lots of field tested applications experience that we can apply to helping our customers make the best use of their Martel BETA calibrators.

We think it’s important that our customer service starts with whoever answers the phone and extends all the way to our president. Our goal is to have no unhappy customers, so be sure to throw those problems our way. We’ll do our best.

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.

Do you need to know more or wish you knew more about flowmeters?

Our friends at OMEGA Engineering have an excellent on-line tutorial in their Transactions material. I think you can also request this in hard copy from them.

The tutorial starts out with some interesting history about the development of flowmeters. I’ll bet you didn’t know that the earliest flowmeters are from around 5,000 BCE!

The material is technical enough to be of interest, but doesn’t really require much beyond algebra and a little knowledge of physics to be understandable.

The topics cover differential pressure type flowmeters, mechanical (positive displacement) flowmeters, various electronic flowmeters including magnetic flowmeters, vortex meters and ultrasonic flowmeters. There’s also a section on mass flow measurement using coriolis and thermal flowmeters.

It’s worth a look. You can find it here.

Many people don’t realize that we make a custody transfer flowmeter calibration kit for the BetaGauge 330-30. This adds a high range pressure module and LTP100A RTD probe to the standard calibrator.

The integral pump and internal sensor are used for the differential calibration portion of the flowmeter. A high pressure external sensor is used for the static portion, and, of course, the RTD provides the data for the temperature compensation calibration of the flowmeter.