Parr Instruments

Photo of Benzoic Acid Calorific Standard, Parr
Calorific standard in powder or pellet form for standardizing all oxygen vessel calorimeters.
Photo of Acid Digestion Vessel Parr 4745
This is the original acid digestion vessel introduced by Parr in 1969 to provide a PTFE lined metal vessel of simple design and minimum cost that can be used safely for routine sample preparation purposes. Its wide acceptance over the intervening years has proved it to be an excellent design for general digestion procedures in which temperatures and pressures are held below 150°C and 1200 psig. It can be used occasionally above 150°C, but at elevated temperatures it becomes increasingly difficult to maintain a tight seal.
Photo of Acid Digestion Vessel Parr 4744
This is a 45 mL modification of the 23 mL, 4749 PTFE lined vessel for users who want additional capacity in this popular model. It is made with the same closure as the 23 mL vessel, using a similar thick-walled PTFE cup, 3-3/4 inches deep inside, with a broad flanged seal. Safety blow out protection is provided with a rupture disc that will release pressure through an opening in the cover. Its maximum temperature and pressure ratings, 250°C and 1800 psig, are the same as for the 4749 model.
Photo of Acid Digestion Vessel Parr 4749
This is a 23 mL, general purpose acid digestion vessel, similar to the original 4745 model but modified for use at higher temperatures and pressures, and provided with safety blowout protection as well. Operating temperatures and pressures up to a maximum of 250°C and 1800 psig are permitted in this vessel using a thick-walled PTFE liner with a broad, flanged seal. The forces required to seal the liner are developed by tightening the bomb cap with a spanner while holding the vessel in a special fixture.