香港传感器技术有限公司
 
Frequently Asked Questions

This page provides answers to our most common questions.

1. What is Krystal Bond Technology?
2. What is so unique about AST's technology in comparison to other technologies?
3. What are the current pressure ranges offered by AST?
4. What kind of pressure references are used by AST's pressure transducers?
5. Can Pressure Sensors and Transducers utilizing AST's Krystal Bond Technology measure from vacuum to positive pressure?
6. Is there a difference between a sensor, transducer, and transmitter?
7. What is the media compatibility of AST's pressure products?
8. What type of mechanical interfaces are offered by AST?
9. What type of electrical interfaces are offered by AST?
10. Can AST's products run from an unregulated power supply?
11. Are AST's products able to withstand electrical interferences, such as EMI/RFI, transient, and ESD?
12. What agency approvals do AST's products meet?
13. Are AST's products approved for Canadian markets?
14. What is meant by "panel mount" pressure sensor?
15. For miniaturization, does AST offer any embedded sensor designs?
16. What is the AST4000 P-T combo?
17. The AST 4000 P-T combo unit has a '1 wire' bus output. What does that mean?
18. What does long-term stability mean? How does it affect the measurements?
19. Do AST's products offer zero & span adjustments?
20. Can AST supply front-end subassemblies for customers to value add in house?
21. What is the best way for me to contact AST with regards to my sensor needs?
22. Does AST have online documentation for their pressure products?
1. What is Krystal Bond Technology?
Krystal Bond Technology is a diffusion process developed by AST to inorganically bond micro-machined semiconductor strain gauges to metallic diaphragms in the presence of high temperatures.

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2.

What is so unique about AST's technology in comparison to other technologies?
The Krystal Bond technology coupled with the unique one piece sensing element design offers many advantages over other technologies for the following reasons:
a. Excellent long-term stability
b. High electrical isolation
c. High temperature operation
d. No leak paths
e. No 'O' rings, welds, or fluid filled cavities
f.  High cyclic life
g. High overload and burst pressure capabilities
h. Wide media compatibility

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3. What are the current pressure ranges offered by AST?
The current one-piece design offers pressure ranges from 0-15 to 0 -30,000PSI (0-1 to 0-2000 BAR) with respect to the day's atmospheric pressure.

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4. What kind of pressure references are used by AST's pressure transducers?
AST offers gage and sealed gage references. For compound pressure requirements, (such as -14.7 to 85PSI, etc.) AST can calibrate sensors with the low electrical point at -14.7 PSI with respect to the day's atmospheric pressure.

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5. Can Pressure Sensors and Transducers utilizing AST's Krystal Bond Technology measure from vacuum to positive pressure?
Yes, Krystal Bond Technology, being highly compensatable, allows vacuum calibration, regardless of volume.

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6. Is there a difference between a sensor, transducer, and transmitter?
Sensor Lowest level of assembly. It only offers mV output and can be used up to 10 feet away from electronics
Transducer Sensor with high-level voltage output with a drive capability up to 30 feet with minimum output signal loss.
Transmitter Sensor with current output, such as 4-20mA; ideal for long transmissions and offers good immunity in noisy environment.

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7. What is the media compatibility of AST's pressure products?
A wide range of liquids and gases are compatible with 17-4 PH and 316L stainless steels. For highly corrosive media, such as H2S, found in oil and gas fields, AST can offer Inconel X-750 or 718. For others, please consult factory.

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8. What type of mechanical interfaces are offered by AST?
AST offers a wide range of threads, such as 1/8"NPT, ?quot;NPT, ?quot;NPT, 7/16-20"UNF, M14 x 1.5 and ?quot;BSP male. 1/8"NPT, ?quot;NPT, and ?quot;NPT are also available in both male and female parts. For others, please consult factory.

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9. What type of electrical interfaces are offered by AST?
Cable with 2ft wire length is the standard interface (AST will provide assembled in-line connectors). Other lengths are available upon request.
Available connectors standard are Packard Metripack 150 series, 3 pin and mini DIN 43560 (8mm contact spacing). Mating connections can be supplied by AST at a charge. Bendix 6 pin metal connectors are available as an option. Please contact AST for more information.

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10. Can AST's products run from an unregulated power supply?
All non-ratiometric pressure transducers and transmitters can operate from an unregulated power supply between 10 and 32VDC. For 4-20mA, it is important to have sufficient supply to maintain the minimum compliance voltage of 9V while driving long cable lengths. Ratiometric units must be supplied with regulated power supply, usually 5V.

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11.

 Are AST's products able to withstand electrical interferences, such as EMI/RFI, transient, and ESD?
Some of AST's pressure products are designed to stand high levels of electrical interference such as EMI/RFI, electrical transients and ESD. These products are called "stand-alone" products. Radiated susceptibility up to 100V/m, transients to +/- 2kV and ESD levels of 8kV are standard features of a stand-alone product and comply with EN50082-2.

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12. What agency approvals do AST's products meet?
AST's products have been tested by UL for the following standards:
a. UL508-ordinary listings for motor control and electrical equipment
b. UL1604-nonincendive (nonsparking) Class I Div. 2, Groups A, B, C, and D for hazardous locations.
c. UL913-Class 1 Div. 1 Groups C and D; Intrinsically safe

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13. Are AST's products approved for Canadian markets?
AST's products have been tested by UL and conform to Canadian Standards (CSA 157 and 213). UL has authorized AST to print the cUL logo on our labels as part of this certification.

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14. What is meant by "panel mount" pressure sensor?
A panel mount is a unique design that replaces the traditional sensors and bulk head fitting with a single design. This allow the media to be kept outside the panel box while maintaining maximum safety of the system. Some applications include gas cabinets, pump controls, natural gas flow control and refrigeration/HVAC.

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15. For miniaturization, does AST offer any embedded sensor designs?
AST offers both threaded and unthreaded miniature units for embedding in manifolds and valves.  Example 3 on the custom design page is an example of a threaded part.

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16. What is the AST4000 P-T combo?
The AST4000 P-T combo unit is a unique product that allows the measurement of pressure and temperature from a single point on the system.

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17. The AST 4000 P-T combo unit has a '1 wire' bus output. What does that mean?
'1 wire' bus system allows both pressure and temperature to be transmitted via serial digital link on a single wire from the sensor to the master controller. The same wire performs the control function prior to data transmission. Up to 128 sensors can be bussed together in a ring system and "polled" when desired.

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18. What does long-term stability mean? How does it affect the measurements?
Long-term stability is normally associated with the change in zero offset due to aging of component and relaxation of the metallic diaphragm over a period of time. It normally causes the zero reading to go high or low over time. Independent tests carried out on AST's products have shown this number to be <.25% under the influence of temperature and pressure cycling for 1500hrs.

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19. Do AST's products offer zero & span adjustments?
AST 4310 (Class 1, Div 2) and AST 4410 (Class 1, Div 1) offer zero and span adjustments. Adjustments are +/-5% for zero and span.

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20. Can AST supply front-end subassemblies for customers to value add in house?
Yes, AST can supply either compensated or uncompensated front-end subassemblies. Electrical interface is by means of the Molex connector, flex strip or hook-up wires.

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21. What is the best way for me to contact AST with regards to my sensor needs?
The best method for prompt response is to use e-mail and mail to info@astsensors.com. You may also call/fax our offices in NJ (Phone: 973-448-1901; Fax: 973-448-1905) or your local factory trained sales representative (please see Local Reps section).

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22. Does AST have online documentation for their pressure products?
Yes, view them here or download the PDF files to your computer.

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