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FAQ Model 420

(Full list of error codes appear at the back of the Operator manual)

Question 1:
Why will the Instrument not start

Answer 1:
Retry ignition sequence after waiting 20 seconds

Question 2:
The flame will not stay alight

Answer 2:
This could be the flame-out detector failing. To test: switch off gas and Air-compressor; switch on instrument and then shine torch/flash light down chimney. If the is detector is working the flame-on light will illuminate. If the light is not working then contact your service provider for a replacement phototransistor assembly ( #41015001)

If the flame-out detector is working then there may be a blockage in the fuel line. Remove the front panel and clear the LEFT HAND restrictor using the nebuliser cleaning wire supplied with the Model 420.

Question 3:
Why will not the instrument blank

Answer 3
The blank solution may not contain any Lithium ( The default mode is peak & ref)

Question 4:
I cannot get any printout.

Answer 4:
a - Check the baud rate on your printer is set to 9600
b - Check the pins on the cable at the 9 pin end are not bent.

Question 5
Why are the results are erratic?

Answer 5
Several reasons:
A - If the nebuliser is blocked, the performance will deteriorate. Check the nebuliser performance section 7.6 in the Operator manual;
B - Is there condensation in the compressed air tube? This is due to high humidity in the atmosphere, which separates out when the air cools under reduced pressure on the outlet side of the pump. Change to water trapped pump such as Sherwood Model 855.
C - Low Air pressure means that there is not enough sample reaching the flame. Increase the air pressure to 12 PSI using the control ( see Operator Manual Figure 2.2 Page 12)