Frequently Asked Questions | SGX Sensortech

FAQS

Can I put a membrane in front of the Pellistor sensor?

Yes, but the response time is likely to be adversely affected. Filter chemistry may affect response to certain gases. Contact SGX  for advice.

Can I put a membrane in front of the Infrared sensor?

A membrane filter is useful to help protect the sensor from ingress of dirt and liquids, which can upset the IR optical cavity. The filter cover will also slow the response of the sensor, depending on the porosity of the filter material.

 

 

Can I put a membrane in front of the Electrochemical sensor?

Yes, but the response time is likely to be adversely affected. Filter chemistry may affect response to certain gases. Contact SGX for advice.

 

Can I put a membrane in front of the Metal Oxide Semiconductor sensor?

Yes, but the response time is likely to be adversely affected. Filter chemistry may affect response to certain gases. Contact SGX for advice.

 

Can Pellistor sensors withstand exposure to the target gas for long periods?

This depends on the level and duration. The longer and higher the concentration, the greater the degree of zero drift and change in (net) sensitivity. The latter is usually a decrease in sensitivity.

 

Can Infrared sensors withstand exposure to the target gas for long periods?

All Infrared gas sensors can withstand exposure to target gas for long periods.

 

Can Electrochemical sensors withstand exposure to the target gas for long periods?

This depends on the level and duration. The longer and higher the concentration, the greater the degree of zero drift and change in (net) sensitivity. The latter is usually a decrease in sensitivity.

 

Can Metal Oxide Semiconductor sensors withstand exposure to the target gas for long periods?

This depends on the level and duration. The longer and higher the concentration, the greater the degree of zero drift and change in (net) sensitivity. The latter is usually a decrease in sensitivity.

 

Do the Pellistor sensors have Intrinsic Safety approvals?

The MPEL is certified ExIa, all other pellistors do not have an intrinsic safety approval.

 

Do the Infrared sensors have Intrinsic Safety approvals?

Certain types are Intrinsically Safe for mining (methane only). Refer to Datasheets for more information.

 

Do the Electrochemical sensors have Intrinsic Safety approvals?

Refer to the Electrochemical Application Notes

 

Do the Metal Oxide Semiconductor sensors have Intrinsic Safety approvals?

No

 

Do the Pellistor sensors have safety approvals?

Some pellistors sensors do have safety approvals. Refer to datasheets and/or Approval Certificates.

 

Do the Infrared sensors have safety approvals?

Some infrared sensors do have safety approvals. Refer to datasheets and/or Approval Certificates.

 

Do the Electrochemical sensors have safety approvals?

No

 

Do the Metal Oxide Semiconductor sensors have safety approvals?

No

 

 

How much Oxygen do Pellistor sensors need to function correctly?

More than 12% oxygen needs to be present in the sample stream.

 

How much Oxygen do Infrared sensors need to function correctly?

None

 

How much Oxygen do Electrochemical sensors need to function correctly?

Sensor will work for at least 24 hrs in 0% O2-otherwise at least several thousand ppm O2 required

 

How much Oxygen do Metal Oxide Semiconductor sensors need to function correctly?

More than 12% oxygen needs to be present in the sample stream.

 

What is the recommended re-calibration period when Pellistor sensors are used in an instrument?

The time period between calibration will be dependant upon the environment in which the sensor will be operating and the required accuracy. A three month calibration period for sensors operating in “normal” conditions could be used. For environments where poisons or inhibitors are likely to be present, the instruments should ideally be “bump tested” before every use, to ensure the sensor has not become poisoned.

 

 

What is the recommended re-calibration period when Infrared sensors are used in an instrument?

The time period between calibration will be dependant upon the environment in which the sensor will be operating and the required accuracy. Typically, a six month recalibration period would be used.

 

What is the recommended re-calibration period when Electrochemical sensors are used in an instrument?

The time period between calibration will be dependant upon the environment in which the sensor will be operating and the required accuracy. Typically, a three to six month recalibration period would be used.

 

What is the recommended re-calibration period when Metal Oxide Semiconductor sensors are used in an instrument?

The time period between calibration will be dependant upon the environment in which the sensor will be operating and the required accuracy. A three month calibration period for sensors operating in “normal” conditions could be used. For environments where poisons or inhibitors are likely to be present, the instruments should ideally be “bump tested” before every use, to ensure the sensor has not become poisoned.

 

What substances can kill a Pellistor sensor?

See Pellistor Application Note 6

 

What substances can kill a Infrared sensor?

None, although care must be taken to ensure the sinter does not get blocked with any particulates.

 

What substances can kill a Electrochemical sensor?

Exposure to high concentrations of solvents such as Acetone can affect the electrodes within the sensor.

 

What substances can kill a Metal Oxide Semiconductor sensor?

The sensors can be affected by exposures to organic silicon compounds and cfc’s. Contact SGX for further advice.

 

Why do readings change when the Infrared instrument is taken down a mine?

This is due to increasing pressure causing an increase in gas density.

 

How accurate are the quoted Pellistor cross-sensitivity values?

Some sensor to sensor variation is observed from the theoretical response (see Pellistor Application Note 3 and the datasheet). Ideally the sensor should be calibrated to the actual target gas or vapour.

What are the recommended storage conditions for a Pellistor sensor?

Sensors are not sensitive to storage temperature. See individual datasheets.

 

What are the recommended storage conditions for a Infrared sensor?

Sensors are not sensitive to storage temperature. See individual datasheets.

 

What are the recommended storage conditions for an Electrochemical sensor?

Sensors are not sensitive to storage in normal temperatures-however prolonged exposure to high temperatures should be avoided.

 

What are the recommended storage conditions for a Metal Oxide Semiconductor sensor?

Sensors are not sensitive to storage temperature. See individual datasheets.

 

What are the Pellistor sensors cross-sensitive to?

Data is available for some gases vapours. Theoretical data is available in the Pellistor Application Notes.

 

What are the Infrared sensors cross-sensitive to?

Please contact SGX or consult datasheet.

 

What are the Electrochemical sensors cross-sensitive to?

Please contact SGX or consult datasheet.

 

What are the Metal Oxide Semiconductor sensors cross-sensitive to?

Please contact SGX or consult datasheet.

 

What do the letters in the Pellistor serial number mean?

The letters in the serial number depict the date of manufacture. Where displayed this date code will record the month / year of manufacture.

 

What do the letters in the Infrared serial number mean?

The letters in the serial number depict the date of manufacture. Where displayed this date code will record the Year / Month of manufacture in the form of two letters.

 

What do the letters in the Electrochemical serial number mean?

The letters in the serial number depict the date of manufacture. Where displayed this date code will record the Year / Month of manufacture in the form of two letters.

 

What factors need to be considered when using a pump before or after the Pellistor sensor?

Some decrease in response time may be seen, care must be taken not to pressurise the sensor which may give elevated responses.

 

 

What factors need to be considered when using a pump before or after the Infrared sensor?

A pump will not affect the response time of the sensor itself, provided it does not create a pressure differential between the outside and inside of the sensor.

 

What factors need to be considered when using a pump before or after the Electrochemical sensor?

Some decrease in response time may be seen, care must be taken not to pressurise the sensor which may give elevated responses.

 

What factors need to be considered when using a pump before or after the Metal Oxide Semiconductor sensor?

The response time maybe reduced, but care is needed not to change the sensor operating temperature.

 

What happens if I expose a Pellistor sensor to pressures outside the quoted operating range?

Larger than normal changes to the sensor zero and sensitivity to the target gas will be seen.

 

What happens if I expose a Infrared sensor to pressures outside the quoted operating range?

IR Gas sensors are not damaged by pressures outside the quoted range, but their signal response will not be linear with gas concentration, unless a special correction algorithm is used – contact SGX gas sensor engineering.

 

What happens if I expose a Electrochemical sensor to pressures outside the quoted operating range?

Larger than normal changes to the sensor zero and sensitivity to the target gas will be seen.

 

What happens if I expose a Metal Oxide Semiconductor sensor to pressures outside the quoted operating range?

Larger than normal changes to the sensor zero and sensitivity to the target gas will be seen.

 

What happens if the gas is at a different temperature than the Pellistor sensor?

The sensor temperature will begin to equilibrate to that of the gas. Changes in the zero and sensitivity to the target gas may be seen.

 

What happens if the gas is at a different temperature than the Infrared sensor?

The sensor and gas inside the sensor will equilibrate to the surrounding temperature. Care will need to be taken to ensure condensation does not form inside the sensor, during any temperature changes.

 

What happens if the gas is at a different temperature than the Electrochemical sensor?

The sensor temperature will begin to equilibrate to that of the gas. Changes in the zero and sensitivity to the target gas may be seen.

 

What happens if the gas is at a different temperature than the Metal Oxide Semiconductor sensor?

The sensor temperature will begin to equilibrate to that of the gas. Changes in the zero and sensitivity to the target gas may be seen.

 

What is the Pellistor sensor housing material?

Certified housings are made mostly from stainless steel.

 

What is the Infrared sensor housing material?

All IR sensors are made in stainless steel

 

Does the gas need to be flowing across the Pellistor sensor?

Stable sensor performance relies in part to diffusion control. A minimum gas flow is required to replace gas reacted by the sensor.

 

 

Does the gas need to be flowing across the Infrared sensor?

No, the sensor works by diffusion. No gas is consumed during exposure to the sensor.

 

Does the gas need to be flowing across the Electrochemical sensor?

Stable sensor performance relies in part to diffusion control. A minimum gas flow is required to replace gas reacted by the sensor.

 

Does the gas need to be flowing across the Metal Oxide Semiconductor sensor?

Stable sensor performance relies in part to diffusion control. A minimum gas flow is required to replace gas reacted by the sensor.

 

What are the recommended power requirements for a Pellistor sensor?

See individual datasheets. The sensors are run in a Wheatstone bridge circuit either in constant voltage or current mode.

 

What are the recommended power requirements for an Infrared sensor?

See Datasheets.

 

What are the recommended power requirements for an Electrochemical sensor?

Sensors work in a potentiostatic circuit which requires very low power (see Electrochemical Sensors Application Notes 2 and 5).

 

What are the recommended power requirements for a Metal Oxide Semiconductor sensor?

See individual datasheets. The sensors are run in a simple circuit at constant voltage.

 

What is the recommended maximum storage period for a Pellistor sensor?

Typically, Pellistors can be stored for up to 12 months.

 

What is the recommended maximum storage period for a Infrared sensor?

Unlimited.

 

What is the recommended maximum storage period for an Electrochemical sensor?

Refer to Datasheets.

 

What is the recommended maximum storage period for a Metal Oxide Semiconductor?

Typically, Pellistors can be stored for up to 12 months.

 

What is the recommended way to connect the Pellistor sensor?

For VQ500 series sensors please use sockets shown here. For other pellistors connect to header legs by soldering or mechanical methods.

 

What is the recommended way to connect the Infrared sensor?

See datasheets for pin out connections . See here for recommended sockets.

 

What is the recommended way to connect the Electrochemical sensor?

See datasheets for pin out connections . For Series 4 sensors, please see here.  For Series 7 sensors please see here.

 

What is the recommended way to connect the Metal Oxide Semiconductor sensor?

For TO39 sensors use sockets or solder to board. For SMD solder direct to board.

What is the Pellistor sensor temperature performance?

All sensors will show a change in sensitivity (and in some cases zero) with temperature.  For more specific information please refer to the relevant datasheet and application note.

 

What is the Infrared sensor temperature performance?

All sensors will show a change in sensitivity (and in some cases zero) with temperature.  For more specific information please refer to the relevant datasheet and application note.

 

What is the Elecrochemical sensor temperature performance?

All sensors will show a change in sensitivity (and in some cases zero) with temperature.  For more specific information please refer to the relevant datasheet and application note.

 

What is the Metal Oxide Semiconductor sensor temperature performance?

All sensors will show a change in sensitivity (and in some cases zero) with temperature.  For more specific information please refer to the relevant datasheet and application note.

 

I have bought a pair of pellistors . Why is there no resistor in the packing tube?

Not all pellistor pairs require a trimming resistor. In this case the label will read ‘ N/R’

 

How many people work at SGX Sensortech?

Across all manufacturing and sales facilities, SGX Sensortech employ approximately 80 people.

What warranty can I expect with SGX sensors?

The warranty offered depends on the type of product purchased.  For more information, either review the product technical datasheet or contact an SGX sales representative or distributor.

Who are your distributors?

Details of our distribution partners can be found in the Distributor section of our website.

 

Are you looking for distributors?

SGX is constantly seeking better ways to serve their customers and working with capable distribution partners is a key part of that strategy.  All of our distributors have a good understanding of how our products work and how they can best support integration into instrumentation; in addition they realise the importance of timely and accurate customer support.  If you think your organisation has similar capabilities and are interested in adding SGX products to your portfolio, then please do not hesitate to contact us.

Can you offer customer specific labels?

We can, and indeed do offer custom labelled product to some of our key customers.  However this service is typically only offered to high volume users of our products in an effort to reduce the level of variation within our product portfolio.

I have the following instrument xxxx, can I buy service spares or replacement sensors from you?

At SGX we have a strict OEM policy which means that we will only sell sensors to proven instrument manufacturers.  If you need service components for your instrument, then please contact the original manufacturer.

Do you have an online store?

SGX do not themselves run an online store.  However our US distributor (CDI) is able to offer this facility and you may purchase sensors direct from their website.

Do you accept credit card payments?

SGX do not accept credit card payments, however our US distributor can offer this facility via their online store.

What are the lead times for your sensors?

The lead time of our products varies depending on the product required.  Please contact your SGX sales representative for further information.

I will be needs to change the address of one the sensors (Module as MiCS-VZ-89TE). Is this possible or do we have to order sensors with different addresses ?

Yes the module can be configured with different I2C-adresses. But in current Software revision it needs to be done with the programmer.

Please contact with us and tell which addresses are suitable for you. We will be preparing for you the new address.

“The VZ89 communication must be set in “standard Mode”: bit rates up to 100 kbit/s”. Can you explain this in more detail ?

The I2C speed grades (standard mode: 100 kbit/sfull speed: 400 kbit/s, fast mode: 1 mbit/shigh speed: 3,2 Mbit/s) are maximum ratings. Compliant hardware guaranties that it can handle transmission speed up to the maximum clock rate specified by the mode.

For our design, we choose the standard-mode (100kbits/s max)… It means that the I2C-master should not communicate with the module faster.

 

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