Frequently Asked Questions

A: * A) At ≦100ppmv of Ethanol in a Natural Gas stream, there will have a negligible effect on the moisture dew point reading

* At 101ppmv of Ethanol in a Natural Gas stream , there will be a measurable effect on the moisture dew point reading on the order of approximately 0.33ppmv moisture.

* EXAMPLE: 100ppmv of Ethanol will not be measurable, but 110ppmv of Ethanol will raise the moisture dew point reading by approximately 3.33ppmv.Methanol behaves in a similar fashion.​

A: Ethanol will interfere with the moisture measurement. Ethanol is a polar molecule that bonds similar to H2O. Although larger than a H2O molecule it still skews the measurement to the wet side. ​

A: In cases such as this where the sensor has been exposed to liquid, the sensors can behave as described. The calibration curve can be affected based on how much water has been deposited on the sensor element, and for how long. In instances where the sensor actually dries out and gives a reading ( such as this one ), the sensor should be recalibrated via the span check before being installed back into the gas stream. If the sensor curve has shifted as suspected, the calibration data stored in the e-prom from the original span check will no longer be valid. If the sensor continues to behave as described in the customer’s e-mail after performing the span-check, then it will need to be replaced. Ambient dew point can be used as a guide when exposing the sensors to ambient air, but remember the sensors need flow to read properly. I would not be too concerned if they do not match the ambient dew point as he describes. ​

A: For up to about 20 meters of cable, the cable compensation setting within the controller will allow to calibrate out the additional capacitance in the longer cable. Above that, it is recommended the unit actually be calibrated with the extra cable attached; providing this is done, long lengths of 200-300 meters can be achieved.​

A: Recommended flow rate is 1-3 SLPM (2-6 SCFH).​

A: Less than 10 watts​

A: Maximum resistive load is 500 ohms.​

A: If the pressure at the sensor and in the process are different, then the pressure adjust allows the reading on the instrument to be adjusted. The sensor pressure is the actual pressure at the sensor. We calibrate at atmospheric pressure, if the sensor is being used at any other pressure, changing the sensor pressure parameter will compensate the instrument display for the sensor pressure. The unit reading will display the correct dew point for atmospheric pressure. 

If the user wants to know the dew point at pressure in their stream, then the gas pressure parameter is used. Entering the value in the gas pressure will convert the instrument reading to the gas stream reading. 

Examples: If the sensor is at 100 psig and the reading on the instrument is -43.7 C dew point, the actual dew point at atmospheric conditions is -60 C. To get the instrument to read -60 C, enter 114.7 psi into the sensor pressure parameter. 

If the sensor is at atmospheric pressure and reading -60 C but the gas stream is at 100 psig, entering 114.7 psi into the gas pressure parameter will have the instrument read -43.7 C. Air and gas driers are usually rated as a dew point at a pressure. This parameter allows the user to match the instrument reading to the drier specification. ​

A: The sensor is not orientation-sensitive. If there is any potential of condensation existing, vertical installation will ensure the liquid runs to the bottom of the sample cell, limiting sensor damage. Therefore, this is recommended and should apply on in-situ installations as well. ​

A: Please see the Moisture Conversion Table here.​

A: Models: 8800A, 8800B & 8800P Procedure: 

1) Turn off power 

2) Hold down the Mode button while powering up. (Alt dSp screen displayed) 

3) Use the Mode button to scroll through the menu until you find the 'Set LoC, or Set Un LoC' screen. 

(whichever was the last setting will be displayed, LoC or Un LoC.) 

4) Use the Up button to change from LoC to Un LoC, Or use the Down button to change from Un LoC to LoC. 

(the reverse action will have no effect) 

5) Press the Pressure Correct button to return to the normal dew point display. 

Model 8800T Procedure: 

1) Press the mode switch to get to the Viewing serial number screen mode (####) 

2) Hold down both the Up and Down buttons to reboot the unit and restart it in the Set-up mode. 

3) Immediately press and hold the Mode button to see Set ALt / dSp 

4) Use the Mode button to scroll through the menu until you find the Set LoC, or Set Un LoC' screen.

(whichever was the last setting will be displayed, LoC or Un LoC.)

5) Use the Up button to change from LoC to Un LoC, Or use the Down button to change from Un LoC to LoC.

(the reverse action will have no effect)

7) Either hold down both the UP and Down buttons to reboot the unit or cut the power and restart. ​

A: Please view the following pages from the manual.​

A: The model 8800P operating on a battery will turn off after 6 minutes when in the measuring position, or 3 minutes when in the dry position. Of course this feature is intended to save the battery, and it cannot be defeated.

For model 8800P with RS-232 and wall transformer option the auto-turn-off can be defeated by plugging it into the wall AC power (the higher voltage defeats the auto-turn-off), or by shorting pins on the DB9 connector.​

A: Yes, it is. The specified response time of the unit is for a step change from -40 to -60°C is 90% in 450 seconds. That is 7.5 minutes for the first 90%. Obviously the next 10% will take longer. Response time for areas outside of this specified range can be longer.

At -90 to -70°C, the user is looking at the response at the very low end of the sensor range, where the response time would be greater.

At constant temp. and pressure, -90 degrees C is equivalent to less than 1 ppm moisture.

This is instrument is not suitable for PPB level measurements.​

A: Any instrument and cable and barrier combination purchased and shipped from the factory as a set is already properly compensated.

One would only need to perform sensor cable compensation if the cable or the barrier is changed or added.

When a compensation is performed, the hookup has to be identical to the way it will be used. The sensor has to be unplugged at the end of the cable. That same end where the sensor is plugged in (refer to attached control drawing​)​ the cable end is where a dark rectangle labeled Intrinsically Safe Apparatus see Note F), needs a temporary means of shorting or opening the cable, then follow the instructions in the user's manual. We have installed systems with up to 1000m of RG6 cable.​

A: If the (analyzer - cable - barrier - sensor) combination were shipped from the factory as a set, then the correct reading is 330ppm.​

A: Formulas are difficult to compute, therefore Teledyne has come up with the moisture calculator program to run for this calculation.​ Please contact us for a copy of the program.

A: 9600 Bits per second, event parity, 8 data bits and 1 stop bit.

This is reported incorrectly in some versions of the device manual which have the data bits at 7, however, 8 is the correct number.​

A: Switch on instrument 

Scroll with Mode button to Serial Number 

Hit Pressure Correct button (this will jump to Set-up Mode). You will now see Alt/dSP 

Use mode button to Scroll to LoC 

Use Units-Up to toggle display to Un/Loc (this will unlock the instrument) 

Use Mode button to scroll to Alt/dSP 

Use units button to select ?blank?. You want no alternative display at all. This is achieved when only Alt/dsp is blinking and in the upper left hand corner

There is the word ?SET? 

Use Mode key to scroll to Un/LoC

Use Units-Down to toggle to LoC (this will lock the instrument)

Hit Pressure Correct. This will transport you back to operating mode.

The display will no longer blink. 

Please refer to Appendix B of the 8800T manual​ on page 37.​

A: Generally speaking, most of the problems that arise with the use of the 8800 Series moisture units arise due to substandard sampling techniques.

The H2O molecule is sticky, and takes a long time to purge out of interconnection tubing, and the other components that separate the sensor from the process being measured.

For us to best understand the problems you are having and recommend a solution, we would appreciate it if you could provide us the following: 

a) a complete description of the gas​(e​s) that you are measuring the H2O in

b) a digital picture of the setup

c) a complete description of every component used in the setup, with particular attention to the wetted materials used

d) a description of the problem you have ​

A: 1. It is recommended that the XTR sensor be returned to Teledyne for recalibration every 12-18 months. The cleaner the gas, the longer it should take between recalibration intervals. The dirtier the gas stream, the shorter the intervals. 

2. A fee will be charged to determine what's wrong with the unit. This evaluation rate is the same if you return just the sensor or both the electronics and sensor. 

3. In the case of the 8800A (panel mount) and 8800B (wall mount), you may return either just the sensor, or both the sensor and electronics. 

If you return just the sensor, these are the likely options:

a. Order a new sensor

b. Wait for their original sensor to be returned and recalibrated. 

You will be required to enter the calibration coefficients / test points, provided in the calibration certificate, into the software via the mode menu on the unit. 

4. In the case of the 8800P (Portable) and 8800T (Transmitter) you must return the complete unit for recalibration.

Notes: 

1. When the unit is first provided, the sensor comes threaded to a desiccant container to keep the XTR sensor free from exposure to moisture. Keep this desiccant container, as it will be re-used to return the sensor to TAI for recalibration. 

2. If the senor is broken in half, is saturated with oil, is corroded or has a foul smell (i.e., from exposure to H2S, etc), the sensor should not be returned for eval / recal purposes. Simply replace the sensor with a new one. ​

A: The reason copper tubing should not be used is most likely related to ability of the copper tube to absorb moisture molecules. The finish of the copper tube is such that it will absorb / desorb moisture continually and it cannot be successfully purged. Please switch to stainless steel tubing. ​

A: The unit has to be unlocked in order to change engineering units permanently. This is to protect installations in the field from engineering units being inadvertently altered, which will result in a change of the output signal, without the DCS system knowing.

When the unit is locked, you can use the UP and DOWN keys display values in other engineering units, but the display will automatically switch back to the units that were selected when the instrument was locked; and the signal output never changes.

To unlock the instrument refer to the manual. Start the instrument in Set-up mode (hold down MODE key while powering the instrument up), use mode button to scroll to the Lock/UnLock mode, hit the UP arrow key. Switch the instrument off and on again; its now unlocked. ​

A: The sensor is replaced by unscrewing the old sensor from the transmitter. Please see the diagram in the sensor installation section of the 8800T instruction manual​ on page 34. ​

A: Yes, but dew points may only go down to -60C or so because of permeability from air of the tubing and leaks at the connections. For the highest integrity measurements, use electro-polished stainless steel tubing and stainless steel connectors. 

A: For example, in this application, if we use 30 kgf/cm2 g (the highest pressure within the unit) as the 'Gas Pressure', and the dew point indicator show us that the dew point is -85°C, then we can be sure that hydrate won't be formed in any other point within the unit (because the pressure in any other points within the unit is lower than 30 kgf/cm2 g) as long as the unit is operated at temperature above -85°C.

But if we use - let's say - 3.7 kgf/cm2 g as the 'GasPressure', then even if we are sure that the hydrate won't be formed at the points which pressure are at 3.7 kgf/cm2, but we won't be sure if the hydrate has already formed at another point where the pressure is 30 kgf/cm2.

For correct results, the instrument should know the pressure at which the sensor measures. Therefore, it is best that the pressure at which the sensor measures is regulated to be fixed, and we usually recommend atmospheric pressure. 

When measuring at atmospheric pressure, the SENSOR PRESSURE should be set at 1kg/cm2 (14.5psi). If the sensor is installed at 3.7kgf/cm2, then the SENSOR PRESSURE should be set at 3.7kgf/cm2 (53.7psi). We assume that the 3.7kgf/cm2 pressure is fixed. 

Use the PRESSURE CORRECT function of the instrument to set the LINE PRESSURE at 29kgf/cm2 (420psi) to obtain the pressure dew point. You can use the ALTERNATIVE DISPLAY function to alternate between the dew point at SENSOR PRESSURE and the dew point at LINE PRESSURE. ​

A: It should be stainless steel fittings with a glass tube. However, it is better to measure flow after the measurement. No matter how good a flow meter, the surface area of sealing surfaces is increased. Water can diffuse directly across the O-rings and seals which will cause trouble with the measurement.​

A: The open message means that either the sensor circuit has opened or that the capacitance level of the sensor has dropped to a very low level. There is a programmed set point in the software that if the capacitance drops below a certain point, it assume the sensor circuit has opened. 

The end user should run the auto calibration as per section 3.4.4.3 in the manual. Before starting the procedure, they should verify that the low dew point and low db values on the sensor bottle are the same as the points in the unit. This is done in the alternate display mode. 

Again I will also stress the point that the sensor should not be left in ambient air. If the ambient dew point is very high it can cause problems. 

The manual calls out not to leave the sensor in room temperature air for more than 1-2 minutes. The assumption is that room temperature will be roughly 70-75F with a dew point not much greater than 20 C. The sensor can withstand higher temperatures but the real issue is the humidity level. High humidity will cause a long dry done period but if condensation forms, the sensor can be damaged. When the word ambient gets used and the sensor shows saturated (+20 C), condensation becomes a concern. Ambient conditions in the Middle East are not a concern but ambient conditions in Southeast Asia can be a problem. 

A: The Dew point reading can be displayed in units of PPM, oC, oF, LBS, or G/M3. By pressing the Up or Down key while in normal operation mode (Viewing Dew point mode).This is in section 3.4.4.1 of the manual.

The default unit for this analyzer is oC, however, from the keypad this can be changed to PPM or any of the other units, and when changed will be retained until changed again.

Page 25 section 3.4.5 covers other Setup states, and changing the viewing dew point units is not included in the 4 of 11 modes that are factory set. 

In this Setup state we are allowed to select an "Alternate display', If ppm were selected in this mode, it will alternate between PPM & oC. (This is most likely what occurred here)

To remove this alternate display, they should scroll thru the alternate display units, until they reach the Blank display, this means there is no alternate display. When the blank display is selected, the PPM unit selected in the "Viewing Dew point" mode will be the only unit displayed.​

A: To properly correct the readings, the unit needs to know that the sensor is at 8 bar (117.6 psia). This value gets entered into the sensor pressure field as you described. The gas pressure field is used when you want the reading to be based on a pressure that is not seen by the sensor. 

Do not make an adjustment to the gas pressure. Otherwise it will double correct.​