All components monitoring procedures involve rinsing the item to be sampled with particle-free solvent, then recovering the solvent and filtering it through an Merck filter for subsequent analysis.
The recovery of particles and reproducibility of the test will depend upon:
The nature of the solvent used. CFC-Free Contact Cleaners, alcohol, and water are commonly used. Once you have chosen a solvent, avoid switching from one to another.
The volume of solvent per unit surface area.
The flow intensity of spray velocity.
The intensity of any mechanical or ultrasonic agitation of the liquid in contact with the surface.
In establishing a test procedure, you must keep the following factors constant as part of the test criteria. The examples that follow are illustrative only. You may analyze the collected liquid by any of the procedures listed in the Analysis Techniques section, although particle counting analyses are most often used. Once established, conduct the test procedure for a given device the same way each time to achieve maximum reproducibility.
Tubing and Hoses Sampling
Short Lengths: Fill the tubing you need to test approximately 3/4 full with a membrane-filtered solvent. Cap each end and turn end over end or flex six times. Decant the solvent directly into a clean glass filter holder or into a clean sample bottle. Process sample for filtration in the laboratory.
Long Lengths: Connect a source of pressurized, membrane-filtered solvent to the test tubing. Place the membrane filter immediately before the tubing to be tested. Collect the solvent from the end of the tubing in a clean sample bottle. (Use 10X the internal tubing volume as a guide to the total solvent volume. If large volumes of solvent are used, it may be necessary to take a sample from the collected solvent.) Process sample for laboratory filtration.
Small Valves and Manifolds Sampling:
Connect the part by means of suitable adapters and clean hoses to a source of pressurized membrane filtered solvent. Collect the solvent at the outlet of the part in a clean sample bottle or pass it through an Merck sampler.
Large Valves and Fittings Sampling:
Transport the part in a clean container protected from plant and machining debris. Remove any protective covers. Hold the component with your gloved hand (preclean the glove if necessary) over a filter holder funnel, a clean sample container or a clean tray. Direct a forceful stream of membrane-filtered solvent over entire component, including inner surfaces and crevices. Collect the entire volume of liquid for analysis. Use approximately 200 mL of solvent per square foot of surface area (2 L/m2). Apply at least 200 mL of flushing solvent, regardless of component size.