Sample Tube

Sample Tube Installation

 

Use the cotton gloves provided in the accessory kit when handling heated surfaces. These cotton gloves are not intended to protect hands when heated surfaces are above 60 °C.

 

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 Kalrez (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. Sample tube collar
  2. O-rings
  1. Open the furnace.
  2. Remove any sample tube stoppers immediately before connecting the sample tube to the analyzer.
  3. Carefully slide the sample tube collar over the open ends of the sample tube. The ferrules should be placed (narrow end down) on the smaller side of the sample tube.
 

For quartz tubes, do not allow the collar 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. Insert the open ends of the sample tube into the openings under the upper panel, aligning the thermocouple in the proper position.
  3. Push the sample tube up into the sample port until it comes to a stop. Push the lever to the left of the sample tube forward until it stops.

  1. If the thermocouple is placed on the outside of the sample tube, clamp it to the tube.
  2. Close and latch the furnace. The furnace will not heat unless closed.

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.
  2. Support the sample tube with one hand and push the sample tube lever to the left to release the sample tube.
  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.

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. 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 when handling heated surfaces. These cotton gloves are not intended to protect hands when heated surfaces are above 60 °C.
  1. Remove the sample tube by holding the tube with your right hand while pushing the sample tube lever back toward the analyzer with your left hand.
  2. 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.

  1. Install a new (or cleaned) analysis port filter in the sample tube fitting.
  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. Insert the open ends of the sample tube into the openings under the upper panel, aligning the thermocouple in the proper position.

  3. Push the sample tube up into the sample port until it comes to a stop. Pull the lever to the left of the sample tube forward until it stops.