FAQ Answers

Product Specific

1) How are Crystal Engineering's products accuracy rated?
Our products are rated in "% of reading" - like deadweight testers - but unlike deadweight testers, they're not affected by ambient temperature (or local gravity). Other gauges are rated in "% of full scale" - like mechanical pressure gauges.

With our products, the XP2i for example, has a 0.1% of reading accuracy down to 20% of full scale range. This means that one XP2i gauge can replace multiple "of scale" gauges (see illustration), leaving fewer gauges to maintain and calibrate every year...

2) What does fully temperature compensated mean?
All digital pressure gauges are "temperature compensated" but when you study the fine print, you will find that temperature can still have a big effect on accuracy. Our products are fully temperature compensated, calibrated in an environmental test chamber, so the accuracy is the same over the entire operating temperature range, and they can be used to measure vacuum. All Crystal Engineering products come with a factory calibration report that proves it meets specifications at 5 different temperatures.

3) How can one of Crystal's "of reading" digital pressure gauge replace multiple "of scale" gauges?
A single XP2i with 0.1% of reading accuracy and a 15 PSI range, for example, can replace multiple 0.1% of full scale gauges from 15 PSI down to 3 PSI with the same accuracy. A 10K XP2i can replace mechanical gauges down to 2K PSI with the same 0.1% of reading accuracy over a remarkable range of 8000 PSI, leaving fewer gauges to maintain and calibrate every year. See illustration.

4) What units of measurement can be used with Crystal Engineering's products?
You can use Crystal Engineering's calculator to convert any units of measurement.You can also add a custom engineering units for torque, force, level or others using our free ConfigXP or ConfigM30 software.

5) What additional features can I add to Crystal Engineering's products?
Depending on the specific product, there are several features that you can add. Some of the available features include:

-DD	Dual Line Display Adds a second line to the display which can be set to indicate peaks, average, leak rate or differential pressure when connected to a second pressure gauge connected via an ordinary DB-9 null modem cable. Great for relief valve or leak testing
-F4	Panel Mounting Allows an XP2i to fit in a 4.5" gauge cut-out. It can also be adapted to fit into 6" or 8.5" gauge cut outs by ordering a flange adapter kit
- RP	Rear Port Fitting The rear port fitting can be ordered separately but is included automatically with the panel mount flange option (F4)
-O	Cleaned for Oxygen Service For applications requiring cleaning for oxygen
DataLoggerXP	DataLoggerXP Allows you to record up to 6000 measurements. The software application handles all of the transfer and saving of data to your computer's hard drive, while the XP2i once authorized, performs all of the actual data collection
ConFigXP	ConFigXP Allows you to customize your gauge by adding or disabling features
FastCalXP	FastCalXP calibration software that allows you to a 10 point up and down calibration can be completed in less than 3 minutes. See Demo

Check out the "Options & Accessories" tab under each product page for the feature details.
XP2i 
XP2i-DP
M1
WT
30 Series

6) What is the uncertainty of Crystal Engineering products?
Uncertainty has to be considered for each individual test done by the customer themselves. There are a number of variables in the uncertainty calculation that Crystal does not control such as the physical setup, operational procedures, and ambient environment. Therefore, the customer must come up with their own calculations that they must justify. However, here is what we looked at.

Our products have an influence on the expanded uncertainty as does the DUT (device under test). For instance, each DUT has a different resolution of readability that directly affects the operator's ability to set the pressure at the correct point in the pressure profile. This will be unique for every series of pressure gauges from every different manufacturer so a user would need to take this information under consideration. It must be noted that we reported an expanded uncertainty with a k=2 for a 95% confidence level. As a result we can suggest the different areas that should be considered for each component and system. They are:

XP2i, M1, 30 Series:  For these products we found that the main drivers of the expanded uncertainty to be: Reference pressure uncertainty (we use various pressure controllers and deadweight testers with different expanded uncertainties); resolution of digital indication uncertainty (depending on the range of the gauge, the resolution of readability changes); repeatability uncertainty (this is the ability of the gauge to repeat measurements such as trying to avoid hysteresis and non linearities). Additionally we considered the following but found their contributions to be minimal at our site due to the construction of our new facility: laboratory ambient temperature, laboratory relative humidity, laboratory ambient pressure. Our expanded uncertainty numbers reflect all of these factors combined together.

GaugeCalXP: the following areas should be considered as to whether they are significant or not: head correction (difference between sensing elements of XP2I and DUT, although considered a bias it is an uncertainty); fluid media (the compressibility of the fluid media is based on the bulk modulus so water is better than alcohol, for instance); ability to purge the comparator of air (at high pressures the gases will dissolve into the liquid media, a poorly purged system will have greater adiabatic behavior); repeatability of the operator to apply pressure using the GaugeCalXP (the ability to actually apply pressure to the desired set point in repeatable manner (this can be evaluated by doing a gauge repeatability and reproducibility test)).

DUT: The DUT has different graduations that should be notated. An operator must be able to determine the lowest readability of the gauge such as 1/5 of a graduation.

System level: Would be affected by: lab temperature, relative humidity and pressure conditions

7) Besides the certificate of calibration that is provided when purchasing an XP2i, do you have other documents that guarantee that the XP2i has the stated accuracy?
The best evidence we have that a particular gauge is compliant to the stated accuracy is the certificate of calibration. Since this document links the serial number to the date of calibration and the standards used, it is the best evidence regarding compliance. No other document is as thorough as the certificate.

Application Specific

1) What constitutes Crystal Engineering's CrystalCalXP calibration system?
Our calibration system includes the GaugeCalXP - pressure comparator that is faster to use than a dead weight tester, with two pressure ports. One port is for a Crystal Engineering digital pressure gauge (XP2i or 33 Series) for reference and the second port is for the gauge to be tested. Then the FastCalXP calibration software records your calibrations. You can do a 10 point up and down calibration in less than 3 minutes including printing out a calibration report. 
The System Includes:

	The FastCalXP software tells you the target pressure to set (using the GaugeCalXP Pressure Comparator) and then records the applied pressure when the needle is on the desired mark. See Demo
	The GaugeCalXP is a portable, self contained, hydraulic pressure generator for the calibration of pressure gauges rated up to 700 bar or 10,000 PSI.
	The XP2i is a very rugged, intrinsically safe, digital pressure gauge that fits in your palm with 0.1% of reading accuracy.

2) How to update firmware on a flashing (or data logger mode) gauge with XP2iUpdate?
Make sure that the batteries are not low. Although the Low Battery icon may not be lit, the batteries may be too weak for programming the gauge. When trying to update a gauge that is continuously flashing all segments (or otherwise does not program properly), select the "Bypass version check" checkbox. This will tell XP2iUpdate not to ask the gauge for the current version, which fails if the gauge is not responding correctly. You also need to check the box if trying to update firmware on a gauge that is in data logger mode. The COM port must be manually selected and not set to "auto".

3)How do I get an XP2i to read an offset pressure?  For instance, I want a 3000 PSI gauge to read 14.7 PSI at zero gauge pressure?
Update the gauge to the latest firmware using XP2iUpdate. Use ConfigXP to define a custom engineering unit with the desired offset.

4) What does ERR 5 or ERR 6 mean?
Firmware was modified to monitor "unusual operation" behavior of the pressure sensor on to prevent false positive readings when sensors were damaged. When these error codes are present the gauge must be returned for sensor replacement. ERR 5 means the pressure counts are out of range and ERR 6 is the temperature counts. Change was implemented on XP2i (R0014), -DD (R0114), DL (R0017), and -DD-MIL (R0001).

5) How to evacuate the air out of the GaugeCalXP to achieve better stability or generate vacuum?
The trick is to use the comparator to generate the vacuum. Do not use this procedure if the test device can be damaged by vacuum.

• With the calibration standard in place, remove the device to be tested.
• Install a short piece of hose going from the device test port to the top of the reservoir. This is to return the fluid expelled in step c to the reservoir. If you do not have a short piece of hose please use paper towels or a shop rag to soak up the excess fluid.
• Rotate the screw handle fully clockwise. Make sure the reservoir does not go totally empty while you do this.
• Connect the device to be tested.
• Fill the reservoir with fluid, almost to the top.
• Rotate the screw handle fully counter-clockwise. Observe the reference gauge - it should start indicating negative pressure as you rotate the screw handle. The GaugeCalXP can typically generate -12.5 psi vacuum at sea level for a device with a small volume.
• As you reach the end of travel, and the comparator's piston reaches the fill point (about 1 cm from the end of travel), you will see the fluid level drop in the reservoir. Unless you are filling a very large device, the volume of fluid in the reservoir should be sufficient to completely fill the system. If not, repeat this procedure, but be ready to fill the reservoir as it drops.
• Before generating positive pressure with the comparator, refill the reservoir.

Company Specific

1) Where did the name "Crystal" come from?
The name CRYSTAL is based on the silicon pressure sensors used in the products that make them perform better and are more stabilized and highly repeatable.

2) What certifications or accreditations does Crystal Engineering have?
Our company's quality management system has been awarded ISO 9001:2000 certification. Our calibration lab has been awarded calibration accreditation to ISO 17025:2005 and ANSI/NCSL Z540-1-1994 by the American Association for Laboratory Accreditation (A2LA), also recognized by ILAC, the International Laboratory Accreditation Cooperation.

3) Why choose Crystal Engineering products?
Our products are more accurate than other pressure equipment as they are rated in "% of reading" - like deadweight testers - but unlike deadweight testers, they're not affected by ambient temperature (or local gravity). Other gauges are rated in "% of full scale" - like mechanical pressure gauges. 
Our products are easy to use, do not require manuals, are rugged, ergonomically designed and battery operated, making them portable. 
We put our customers before other considerations so that they can complete the task for which our equipment is purchased.

4) Why should you send your Crystals for repair and calibration to Crystal Engineering?
We know your Crystal like no one else. Our services include:

• Crystal Engineering's Calibration Laboratory is A2LA Accredited and recognized by ILAC
• Annual ISO 17025 re-calibration services and certificates 
• Certificates are accepted in more than 80 countries
• Annual intrinsic safety inspections
• All calibration reports include test data
• Automatic free firmware updates
• Calibration certificates are archived and can be reprinted from our database
• Repair services 

Take advantage of our re-calibration and repair services by simply clicking on the RMA form and filing in the product information.