Apex Instruments stocks a variety of fiber thimbles for in-stack particulate sampling. The thimbles are seamless, high purity filters and available from a choice of two different materials: borosilicate glass fiber and quartz fiber. borosilicate glass fiber thimbles are acid washed to reduce the trace metal content to an absolute minimum. Quartz fiber thimbles are strengthened with alumina and are prefired at 900°C for 2 hours during manufacturing to stabilize the weight prior to use. The gas collection efficiency of the thimbles is 99.9% (0.3 micron DOP). The 25x90mm thimbles specifically manufactured for stack sampling and tapered for ease in loading. Cellulose thimbles are available upon request.

Glass Fiber Thimbles

Quartz Fiber Thimbles

Transport Tube Accessories

Alundum® Thimbles are typically used for in-stack filtration for process-engineering studies when a large sample is needed for analyses. These thimbles are made from fused alumina oxide and remain very constant in weight and can be re-used an infinite number of times. We offer two different porosity thimbles that can be used in our SFA-300 thimble holder. The medium porosity retain particles 5 micron and larger and the coarse retain particles 20 micron and larger.