|Frequently Asked Questions
|How long will it take to ship my order?
|If you need a specific lead time, or are interested in large quantities, call us at 800-942-0315. Normal lead time is about 15 business days after receipt of your order. Occasionally, high demand may result in longer lead times. Gauges with modifications or certain options may have a longer lead time.
|What do I get with my gauge?
|A data sheet with specifications and instructions. Also included is a Certificate of Conformance stating NIST traceability and conformance to specifications.
|Where are Cecomp products manufactured?
|Cecomp Electronics is located northwest of Chicago, Illinois USA. All products are designed and manufactured by us in our Libertyville, Illinois factory. "Made in USA" is indicated on the front of each gauge and on the box label.
|How do I select the right pressure range?
It is traditional to choose a mechanical gauge with a pressure range that is twice the working pressure. This give best accuracy since typical mechanical gauges are more accurate near the middle of their range. This also gives some protection against accidental overpressure or pressure spikes.
|What is "gauge reference?"
|Most gauges are referenced to ambient pressure which is called Gauge reference. The readings are not affected by atmospheric pressure changes. This means that the gauge will read zero with no pressure applied and continue to read zero as atmospheric pressure changes.
Gauges 1000 psi and over use sealed reference transducers which are referenced to a fixed value of 14.7 psia (normal atmospheric pressure). At these higher pressures there is no noticeable difference in operation.
|What is "absolute reference?"
|Absolute reference gauges use absolute vacuum as a zero reference and thus will read zero at high vacuum and atmospheric pressure with the gauge port open to ambient. The gauge reading will vary with barometric pressure and altitude. Since barometric pressure is constantly changing, the gauge's reading will continuously change when the gauge port is open to atmosphere, or if the system to which it is attached changes in volume or pressure with response to atmospheric pressure changes.
As vacuum is applied, the readings will decrease, eventually reaching zero when full vacuum is applied.
Absolute reference gauges are not available in ranges below 15 psi because the transducer would always be in an over range condition at normal atmospheric pressures.
|Why does my absolute reference gauge show a different pressure than the local weather report or airport barometer?
|Atmospheric pressure is affected by high and low pressure weather systems and how high the measuring station is above sea level. For weather barometer readings to make sense it is desirable to remove the effect of weather station altitude.
A weather barometer reading is corrected to a hypothetical sea level reading by taking into account the altitude, pressure reading and temperature.
An altimeter reading is corrected by taking into account the altitude and pressure reading. See the National Weather Service Handbook for more information and refer to Chapter 11 for details.
|What do you mean by 3-1/2 and 4 digit displays?
|A gauge's range and resolution is determined by the number of digits that can be shown on the display. LCDs (Liquid Crystal Displays) used for digital readouts are available with various numbers of digits.
The one used most commonly for Cecomp Falcon Gauges reads up to 1999. This type of display also has decimal points that can be used for lower ranges such as 19.99 or 199.9.
Since the left most digit can only be a 1 or turned off, it is known as a "half digit". The other three digits can display anything from 0 through 9 and thus are called full or whole digits. Thus a 1999 display is known in the electronics industry as a 3-1/2 digit display.
Although the term "half digit" to describe a 1 may not make sense, this description originated in the early days of digital displays and has been around ever since. You may also hear the term "3/4 digit" to describe a display that reads up to 3999 (left most digit either reads off, 1, 2, or 3) although it is not used in our products at this time.
Higher ranges such as our 3000 and 5000 psi ranges require the use of a 4 digit display. This type of display has 4 full digits and can read to 9999. Because this type of display has different characteristics than the more common 3-1/2 digit display, specifications such as battery life will be different.
|How is accuracy calculated?
|Accuracy calculations are based on the characteristics (linearity, hysteresis, repeatability) of the transducer and supporting electronics, range of the transducer, as well as the display resolution.
It is expressed as a percent of full scale of the transducer plus the round-off error of the right most (least significant) digit. This round-off error has to do with the fact that the analog output of the pressure transducer needs to be rounded up or down when it is converted to a digital readout. This produces a 1 digit uncertainty in the right-most digit in the display which can not be ignored. Sometime the "±1 LSD" is left off of the specifications, but it is safe to assume it should be there.
The accuracy statement is typically stated as ±0.25% FS ±1LSD another way of stating this would be ±(0.25% FS +1LSD). For example, lets use a 100 psi gauge; ±0.0025 X 100psi = ±0.25 psi. Since this range has a resolution of 0.1, we round the 0.25 error up to ±0.3. Then we add a last digit uncertainty of ±0.1 to get a calculated accuracy of ±0.4 psi. Our gauges are conservatively rated and generally are well within the stated accuracy limits.
|What is the High Accuracy (±0.1%) option?
|When a gauge is ordered with the "-HA" High Accuracy option, it is linearized and tested until it meets the high accuracy specification.
Certain ranges don't lend themselves to the high accuracy option due to the range and the available display resolution. For example, a 30 psi gauge with 0.1 resolution would have the same calculated accuracy in both ±0.25% FS ±1 LSD and ±0.1% FS ±1 LSD versions due to fact that error is rounded up (we can't ignore possible error).
A gauge in this range would require one of our models with a 4 digit display (0.01 resolution) to take advantage of the high accuracy specification. You should be aware that the added resolution tends to increase drift of the last digit in some ranges.
The High Accuracy is available for the analog output on any gauge with an analog output. For these gauges the high accuracy linearization specification applies only to the analog output.
|Will the gauge be damaged if I drop it?
|Generally, no. An occasional fall from a reasonable height (6 ft. or less) should not damage the gauge, however the case may become chipped. For portable applications we recommend the Rubber Boot (item RB) to help protect the gauge.
|Do you offer other models?
|If you are an OEM and have a special gauge requirement, please feel free to contact us with your specifications. Cecomp Electronics has extensive experience in manufacturing custom and OEM pressure and vacuum instrumentation.
|What about calibration?
|All Cecomp gauges are calibrated at the factory on equipment traceable to NIST. There is no need to calibrate the gauge before putting it in service.
Please be aware that absolute reference gauges will read barometric pressure when the port is exposed to atmosphere and it is normal for the gauge to respond to constantly changing atmospheric pressures.
The gauges have zero and span potentiometers, internal push buttons or a keypad. See our calibration guide for instructions.
Gauge reference gauges can be zeroed at any time if the gauge port is exposed to the atmosphere. Span calibration should only be done with the gauge connected to accurate calibration equipment.
Calibration of absolute reference gauges should only be done with the gauge connected to accurate calibration equipment designed for that purpose.
The recalibration interval depends entirely on the customer's application and quality standards. Many customers check their instruments annually, but some applications require more frequent intervals depending on severity of use and the customer's quality guidelines. Gauges can be returned to us or any metrologist for recalibration.
|Why does NIST traceability calibration cost more?
|A customer's quality standards often requires a gauge to be traceable to NIST standards. It costs several thousand dollars per year to maintain NIST traceable instrumentation for each of the ranges we offer. Instrumentation must
be sent in annually for recertification. This requires duplicate equipment for each range so production is not interrupted.
Our calibration prices are comparable to other metrology labs. Our gauges are easy to calibrate and can be returned to us or any metrologist for recertification.
|Can I use a Gauge Isolator with my Cecomp gauge?
|Yes, you can use a gauge isolator with Cecomp gauges except for the older DPG500 series. Cecomp DPG1000, F4, and F16 series gauges have 316 Stainless Steel wetted parts, so often an Isolator is not needed unless the media is incompatible with stainless steel.
Chemical compatibility data is commonly available from sources such as coleparmer.com or the Compass Corrosion Guide.
Please be aware that a gauge isolator can degrade the accuracy and sensitivity of any gauge it is attached to. Refer to the gauge isolator manufacturer's data for more information.
Please remove the isolator from any gauge you send to us for calibration or service. Cecomp is not equipped to install, service, or refill gauge isolators. This service is generally available from your local gauge distributor. Your local gauge distributor may also be able to recalibrate your Cecomp gauge.