125 mL & 200 mL, 250 °C, 1900 psig
The 4748 and 4748A vessels are the largest of all Parr acid digestion vessels. The 4748 has a 125 mL, removable PTFE cup in a stainless steel body with six cap screws in the screw cap to seal the flanged PTFE cup. An expandable wave spring maintains continuous pressure on the seal during the cooling cycle when PTFE parts might otherwise relax and leak. Stirring can be provided with a magnetic stir bar. The 4748A is a 200 mL modification of the 125 mL, 4748 PTFE lined vessel for users who want additional capacity in this model.
A safety blow-off above the PTFE cup will release pressure through an opening in the vessel head if pressure should accidentally reach the 3500 psi range. For safe operation, pressures in these vessels should never exceed 1900 psi and temperatures must not exceed 250 °C. Operations should be conducted well below these limits whenever possible due to the potential destructive forces in a large vessel charge. It also is advisable to test any new procedures for safety in one of the smaller vessels before scaling up to these sizes. A wrench for the cap screws is furnished with these vessels. No other accessories are required.