Sample Tube

  The equipment images in this document may differ slightly from your equipment, however the instructions are the same unless otherwise noted.

Sample Tube Installation

  Ensure the furnace has cooled to ambient temperature before installing tubes. It is a good practice to wear the cotton gloves provided with the instrument when installing sample tubes.
 

Wear latex gloves when handling the quartz sample tube. The natural oils in human skin can chemically damage and weaken the quartz tube. It is also important that the sample tube and its components, as well as the sample and exhaust ports, be clean and free of debris. Dust particles from quartz wool or the insulator disc of previous analyses may adhere to the port and/or components, preventing a proper seal of the sample tube.

 

Use only KalrezTM (or equivalent) O-rings. Kalrez is rated for both chemical and temperature suitability in this application. O-rings of other materials could burn, melt, or decompose.

Sample Tube Parts
Item Description
A Retaining nuts
B Two part ferrule set
C O-ring with filter
D O-ring
E Stem seal (part 1)
F Stem seal (part 2)
G Seal frit
  1. Carefully slide the sample tube retaining nuts and ferrules over the open ends of the sample tube. The larger diameter nuts and ferrules should be placed on the larger side of the tube, and the smaller diameter nuts and ferrules should be placed (narrow end down) on the smaller side of the sample tube.
 

For quartz tubes, do not allow the nuts to slide down rapidly to the curved portion of the tube. This could damage the tube.

  1. Place an O-ring around each opening of the sample tube.
  2. Remove any sample tube stoppers immediately before connecting the sample tube to the analyzer.
  3. Insert the open ends of the sample tube into the openings under the upper panel, aligning the thermocouple in the proper position. See Sample Thermocouple.
  4. Push the sample tube up into the sample port until it comes to a stop. Tighten the fittings by turning the retaining nuts until finger-tight.
 

Do not overtighten the analysis port fittings — doing so may break the quartz sample tube. The O-rings are sealed when the fittings are finger-tight.

  1. If the thermocouple is placed on the outside of the sample tube, clamp it to the tube. See Use the Thermocouple Clamp.
  2. Close and latch the furnace. The furnace will not heat unless closed. The pressure controller will also be disabled when the furnace is open.

Sample Tube Removal

  The furnace and sample tube may remain very hot for some time after analysis has ended. The sample tube retaining nuts are extremely hot, approximately 110 ºC. Use extreme caution!

It is recommended to allow the furnace and sample tube to return to ambient temperature before touching them. If the sample tube has cooled, use rubber gloves when removing it. If it is still hot, use the cotton gloves provided.

  1. Unlatch and open the furnace.
  Support the sample tube retaining nuts so that they do not fall rapidly out of the analyzer. This may damage the sample tube.
  1. Loosen the sample tube retaining nuts, be very careful and support them. As the nuts are loosened, support the sample tube and pull it gently down out of the analyzer. When the nuts are sufficiently loose, the sample tube, retaining nuts, ferrules, and O-rings should slide out of the analyzer. If necessary, use the extractor tool to pull the O-rings out of the ports.
  2. Inspect the O-rings for cracks or other damage that might cause leaks. If the O-rings are cracked or damaged, replace them before reinstalling the sample tube. Additional O-rings are shipped with the analyzer. Otherwise, clean, dry, and re-install the O-rings.
 

Use only KalrezTM (or equivalent) O-rings. Kalrez is rated for both chemical and temperature suitability in this application. O-rings of other materials could burn, melt, or decompose.

Sample Tube Filter or O-ring Replacement

A frit filter is used to protect the analyzer internal components from contaminants that may be forced out of the sample tube during an analysis. As the analyzer is used, the filter may gradually become clogged with trapped particles. If the filter does become blocked, it must be removed and cleaned or replaced. One indication of a clogged filter is a sample pressure greatly exceeding atmospheric pressure. See Show Instrument Schematic. The nominal sample pressure reading should be a few mmHg above atmospheric pressure

  1. Loosen the analysis port fittings while holding the sample tube.
  The sample tube and nearby components may be hot. Allow the sample tube to cool before removing it.  Use the cotton gloves provided in the accessory kit to remove the sample tube before it has cooled. Rubber gloves may be used to handle the sample tube when it has cooled.
  1. Carefully remove the sample tube by unscrewing the retaining nuts. Do not allow the nuts to slide down onto the curved portion of the sample tube or the tube may break.

  1. Remove the left (smaller) sample tube fitting (it has a tube within a tube).
  1. Use a small diameter probe to remove the O-ring and frit filter disk from the sample tube fitting.
  2. Install a new (or cleaned) analysis port filter in the sample tube fitting.
 

Use only KalrezTM (or equivalent) O-rings. Kalrez is rated for both chemical and temperature suitability in this application. O-rings of other materials could burn, melt, or decompose.

  1. Inspect the O-ring for cracks or cuts. If the O-ring is damaged, replace it with a new O-ring. Otherwise, clean the O-ring, dry it, and place it in the sample tube fitting. Ensure the O-ring is securely in place.
  2. Place the left sample tube fitting back into position and tighten it slightly.
  3. Reinstall the right sample tube fitting and sample tube, then tighten both fittings.
 
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