The Alcotest CH 237 is a breath testing device that uses alcohol detection gas tubes to determine the approximate blood alcohol concentration of an individual. The Alcotest CH 237 was first produced in 1953 and concluded production in February 2016 after 63 years.  

 

Both ends of an Alcotest tube are broken off using the break off husk on the upper right side of the plastic green case.  The tube is inserted into the measuring bag. A red mouth piece is removed from its sterile packet and placed onto the other end of the Alcotest tube. The person must blow into the tube until the measuring bag is full, this must be done in more than 10 seconds, but less than 20 seconds. If alcohol is present the yellow reagent in the tube will turn green. The length of the green colouring will determine the approximate blood alcohol of the user.  

 

Although this example of the Alcotest CH 237 has the old layout with all 10 tubes and mouth pieces being located at the bottom section of the case, it has been manufactured with the 1977 mini instruction booklet which depicts the later version of the Alcotest.   

 

The sticker on the outside of the case is stamped “Labormuster Unverkäuflich” where the expiration date should be. The best translation would be “Laboratory pattern (sample) – Not for sale”.