Why does the output signal response seem much less than what it should be?

Answer: Miniature PIDs in the market place have detection chambers that are not designed to have a pump pulling a sample of gas through them. Having not been designed for inline pumped systems they suffer from the problem of drawing much local air in from around the pellet and thus cannot draw in a gas sample from a distant point through a piping network.

However ISL MiniPID has been designed so that it can be used in pumped systems enabling the drawing forth of a sample gas supply from a remote source. This is done by carefully sealing around the lamp, detection cell and electronics module. Also a flat sealed front surface is provided for the OEM user to press a gasket seal against to form the outside sealing.

However there is slight leakage through the layered construction of the cell and thus depending upon the pressure differential between the cell and the local environment will vary the amount of inward bound leakage through this leak path.

Clearly if there is a positive pressure (MiniPID being after the pump) then this will leak into the local environment and not be a problem (unless there are further sensors downstream). However is does present a problem because pumps have terrible ‘hang-up’ problems especially if a large concentration of VOCs have just been detected.

Thus it is advantageous to place the pump after the MiniPID which will cause a negative pressure differential between the cell and the local environment. Thus if there are leakage paths into the cell from the local environment then the gas sample drawn in from a remote source will be reduced in concentration within the detection cell leading to a reduction in electrical output signal.

To reduce this problem, it becomes necessary to either reduce the pressure differential between the interior of the cell and the outside local environment, or place an additional sealing o’ring on the outside of the MiniPID module.

Note: for further information please refer to the diagram in the accompanying PDF document.

 

Why does my gas detection system hang up for a long period of time after a large signal?

Answer: Miniature PIDs in the market place have detection chambers that are not designed to have a pump pulling a sample of gas through them. Having not been designed for inline pumped systems they suffer from the problem of drawing much local air in from around the pellet and thus cannot draw in a gas sample from a distant point through a piping network.

However ISL MiniPID has been designed so that it can be used in pumped systems enabling the drawing forth of a sample gas supply from a remote source. This is done by carefully sealing around the lamp, detection cell and electronics module. Also a flat sealed front surface is provided for the OEM user to press a gasket seal against to form the outside sealing.

However there is slight leakage through the layered construction of the cell and thus depending upon the pressure differential between the cell and the local environment will vary the amount of inward bound leakage through this leak path.

Clearly if there is a positive pressure (MiniPID being after the pump) then this will leak into the local environment and not be a problem (unless there are further sensors downstream). However is does present a problem because pumps have terrible ‘hang-up’ problems especially if a large concentration of VOCs have just been detected.

Thus it is advantageous to place the pump after the MiniPID which will cause a negative pressure differential between the cell and the local environment. Thus if there are leakage paths into the cell from the local environment then the gas sample drawn in from a remote source will be reduced in concentration within the detection cell leading to a reduction in electrical output signal.

To reduce this problem, it becomes necessary to either reduce the pressure differential between the interior of the cell and the outside local environment, or place an additional sealing o’ring on the outside of the MiniPID module.

Note: for further information please refer to the diagram in the accompanying PDF document.

Additional notes:

It is of paramount importance never to use soft plastic materials upstream of a PID detector else interminably long delays will be experienced in ‘clear-down’ responses. If plastic materials must be used then use PTFE, or the equivalent. Perhaps use Delrin in machined parts. It is always best to use small stainless steel capillaries for the following reason:

• To improve response times always reduce the volume upstream of a detector.
• To improve clear-down times always flush any ‘dead-volumes’ upstream to detector.

Note: these points are also covered in the accompanying PDF document.

 

How can I improve my response time to contamination overload?

Answer: Miniature PIDs in the market place have detection chambers that are not designed to have a pump pulling a sample of gas through them. Having not been designed for inline pumped systems they suffer from the problem of drawing much local air in from around the pellet and thus cannot draw in a gas sample from a distant point through a piping network.

However ISL MiniPID has been designed so that it can be used in pumped systems enabling the drawing forth of a sample gas supply from a remote source. This is done by carefully sealing around the lamp, detection cell and electronics module. Also a flat sealed front surface is provided for the OEM user to press a gasket seal against to form the outside sealing.

However there is slight leakage through the layered construction of the cell and thus depending upon the pressure differential between the cell and the local environment will vary the amount of inward bound leakage through this leak path.

Clearly if there is a positive pressure (MiniPID being afterthe pump) then this will leak into the local environment and not be a problem (unless there are further sensors downstream). However is does present a problem because pumps have terrible ‘hang-up’ problems especially if a large concentration of VOCs have just been detected.

Thus it is advantageous to place the pump after the MiniPID which will cause a negative pressure differential between the cell and the local environment. Thus if there are leakage paths into the cell from the local environment then the gas sample drawn in from a remote source will be reduced in concentration within the detection cell leading to a reduction in electrical output signal.

To reduce this problem, it becomes necessary to either reduce the pressure differential between the interior of the cell and the outside local environment, or place an additional sealing o’ring on the outside of the MiniPID module.

Note: for further information please refer to the diagram in the accompanying PDF document.

Additional notes:

It is of paramount importance never to use soft plastic materials upstream of a PID detector else interminably long delays will be experienced in ‘clear-down’ responses. If plastic materials must be used then use PTFE, or the equivalent. Perhaps use Delrin in machined parts. It is always best to use small stainless steel capillaries for the following reason:

• To improve response times always reduce the volume upstream of a detector.
• To improve clear-down times always flush any ‘dead-volumes’ upstream to detector.

Note: these points are also covered in the accompanying PDF document.

 

How can I speed up my response time?

Answer: Miniature PIDs in the market place have detection chambers that are not designed to have a pump pulling a sample of gas through them. Having not been designed for inline pumped systems they suffer from the problem of drawing much local air in from around the pellet and thus cannot draw in a gas sample from a distant point through a piping network.

However ISL MiniPID has been designed so that it can be used in pumped systems enabling the drawing forth of a sample gas supply from a remote source. This is done by carefully sealing around the lamp, detection cell and electronics module. Also a flat sealed front surface is provided for the OEM user to press a gasket seal against to form the outside sealing.

However there is slight leakage through the layered construction of the cell and thus depending upon the pressure differential between the cell and the local environment will vary the amount of inward bound leakage through this leak path.

Clearly if there is a positive pressure (MiniPID being after the pump) then this will leak into the local environment and not be a problem (unless there are further sensors downstream). However is does present a problem because pumps have terrible ‘hang-up’ problems especially if a large concentration of VOCs have just been detected.

Thus it is advantageous to place the pump after the MiniPID which will cause a negative pressure differential between the cell and the local environment. Thus if there are leakage paths into the cell from the local environment then the gas sample drawn in from a remote source will be reduced in concentration within the detection cell leading to a reduction in electrical output signal.

To reduce this problem, it becomes necessary to either reduce the pressure differential between the interior of the cell and the outside local environment, or place an additional sealing o’ring on the outside of the MiniPID module.

Note: for further information please refer to the diagram in the accompanying PDF document.

Additional notes:

It is of paramount importance never to use soft plastic materials upstream of a PID detector else interminably long delays will be experienced in ‘clear-down’ responses. If plastic materials must be used then use PTFE, or the equivalent. Perhaps use Delrin in machined parts. It is always best to use small stainless steel capillaries for the following reason:

• To improve response times always reduce the volume upstream of a detector.
• To improve clear-down times always flush any ‘dead-volumes’ upstream to detector.

Note: these points are also covered in the accompanying PDF document.

 

How do we reduce the gas path leakage into the MiniPID Cell?

Answer: Miniature PIDs in the market place have detection chambers that are not designed to have a pump pulling a sample of gas through them. Having not been designed for inline pumped systems they suffer from the problem of drawing much local air in from around the pellet and thus cannot draw in a gas sample from a distant point through a piping network.

However ISL MiniPID has been designed so that it can be used in pumped systems enabling the drawing forth of a sample gas supply from a remote source. This is done by carefully sealing around the lamp, detection cell and electronics module. Also a flat sealed front surface is provided for the OEM user to press a gasket seal against to form the outside sealing.

However there is slight leakage through the layered construction of the cell and thus depending upon the pressure differential between the cell and the local environment will vary the amount of inward bound leakage through this leak path.

Clearly if there is a positive pressure (MiniPID being after the pump) then this will leak into the local environment and not be a problem (unless there are further sensors downstream). However is does present a problem because pumps have terrible ‘hang-up’ problems especially if a large concentration of VOCs have just been detected.

Thus it is advantageous to place the pump after the MiniPID which will cause a negative pressure differential between the cell and the local environment. Thus if there are leakage paths into the cell from the local environment then the gas sample drawn in from a remote source will be reduced in concentration within the detection cell leading to a reduction in electrical output signal.

To reduce this problem, it becomes necessary to either reduce the pressure differential between the interior of the cell and the outside local environment, or place an additional sealing o’ring on the outside of the MiniPID module.

Note: for further information please refer to the diagram in the accompanying PDF document.

Additional notes:

It is of paramount importance never to use soft plastic materials upstream of a PID detector else interminably long delays will be experienced in ‘clear-down’ responses. If plastic materials must be used then use PTFE, or the equivalent. Perhaps use Delrin in machined parts. It is always best to use small stainless steel capillaries for the following reason:

• To improve response times always reduce the volume upstream of a detector.
• To improve clear-down times always flush any ‘dead-volumes’ upstream to detector.

Note: these points are also covered in the accompanying PDF document.

 

How do we know if the short circuit bridge has been removed?

Answer: Consider the short circuit is on the vertical plane that runs up through the 8 layers of pcb material. All the layers are plated through holes except a 0.3 mm annulus in an FR4 pcb just below the top flexi-layer. Thus remove the solder plug sufficiently to see this FR4 non-plated annulus within the top 0.3 mm of the surface. All the solder need not be removed from the bottom as the link is made at the top.

Thus the best method to determine if this solder plug has been removed is to use a DVM on "Continuity" and touch the +V supply pin and to place the other probe in the very bottom of the hole and check for open circuit. Ensure that the probe in the hole does not touch (= short circuit across the bridge in) the wall.

There are no internal test ports other than this technique to determine the success of removing the solder plug and hence bringing into operation the internal voltage regulator.

 

How do we change the voltage range on the MiniPID Cell?

Answer: To give maximum flexibility to the OEM user the MiniPID cell has two options.

It is able to operate between 3.0 V and 3.6 V with jumper in place, and 3.6 V to 20 V (maximum applied voltage) with jumper removed.

The 3.0 V to 3.6 V is given to allow the OEM user to directly run from a single lithium ion battery through a low dropout voltage regulator, or a boost/buck switch mode regulator.

Were perhaps the adventurous OEM user might desire to adjust the voltage to trade-off advantages against disadvantages as describe in the manual.

The 3.6 V to 20 V option allows a wide supply voltage range to be applied to the module giving an internal regulated supply voltage fixed at 3.3 V.

The link is actually a solder blob/plug that vertically links through the layers of the pcb assembly and can be made or removed externally by the OEM user.

It is located on the underside of the module next to the three pins.

If the link has NOT been made then a very visible 2 mm diameter gold plated ‘cavity well’ will be very visible and the closed off base at the bottom will have a small plated-through via.

If the link has been made there will be a very visible 2 mm wide soldered area.

Use a soldering iron either to add solder to make the link = 3.0 V to 3.6 V operation to fully fill the ‘cavity well’. OR:- Use a soldering iron and a solder sucker tool to remove the solder to form ‘a well’ = 3.6 V to 20 V operation.

 

What is a MSDS for PID Cleaning Compound?

Answer: MSDS stands for Material Safety Data Sheet. This is a guide to cautions, hazards and first aid measures you need to be aware of when using DRY POWDER GAMA ALUMINA.