Particulate contamination requirements

Xpert Rule is widely used in industrial and scientific applications, one of them performed in cooperation with NASA and Rockwell Aerospace. It is called NASA s Contamination Control Engineering Design Guidelines Expert System and was developed by Rockwell International s Space Systems Division. It was developed for education in contamination control processes and is designed as an interactive guide to assist with quantifying contamination for sensitive surfaces. The tool enables the user to quantify molecular and particulate contamination requirements for solar arrays, thermal control surfaces, or optical sensors [24],... 

Filter life Measure of the duration of a filter s useful service. This is based on the amount of standard contaminant required to cause differential pressure to increase to an unacceptable level-typically 2-4 times the initial differential pressure, a 50-80% drop in initial flow, or a downstream measure of unacceptable particulate. Filter media A porous material for separating suspended particulate matter from fluid. 

Hydraulic fluid contamination may be described as any foreign material or substance whose presence in the fluid is capable of adversely affecting system performance or reliability. It may assume many different forms, including liquids, gases, and solid matter of various composition, sizes, and shapes. Solid matter is the type most often found in hydraulic systems and is generally referred to as particulate contamination. Contamination is always present to some degree, even in new, unused fluid, but must be kept below a level that will adversely affect system operation. Hydraulic contamination control consists of requirements, techniques, and practices necessary to minimize and control fluid contamination. 

Test method ASTM D-2276, Particulate Contaminant in Aviation Fuel by Line Sampling, requires filtration of fuel through a 0.8-micron filter. Caustic neutralized corrosion inhibitor salts can block these filters and slow down the filtration of fuel enough to cause failure of this ASTM test. 

A central housekeeping vacuum is very useful in keeping contamination under control. While wet-and-dry versions of the central vacuum are available, the manner in which each is to be used should be carefully reviewed to ensure that it is in keeping with the sanitary requirements of the facility. A common housekeeping procedure addresses spills with local clean-up and uses a dry-type central vacuum for dry particulate contaminants. 

Sterility testing requires a strict control of microbial contamination challenge from outside the controlled environment, but not of the particulate contamination liberated by the process itself. Hence, a positive-pressure isolator in a controlled environment, using... 

When designing a local exhaust ventilation system for a process that generates dust particles, it is important to consider the minimum air velocity. The minimum air velocity is the velocity required to prevent settling of dust particles in the air ducts. The minimum velocity is a function of dust particle size and particle density. Listed in the table below are the minimum air velocities recommended for the transport of various types of particulate contaminants. 

An important goal in bubbler design is to break the larger bubbles into smaller bubbles, which allows more gas surface to be scrubbed. This is usually accomplished with screen mesh of various sizes, or porous media such as aquarium stones. However, if too fine a mesh or porous material is used to break up the bubbles, particulate contaminants will sooner or later clog the fine mesh or the pores of the dispersal stone. If a bubbler is designed for easy disassembly, then the mesh or stone can be cleaned or replaced, and this may not be a concern. Also, fine porous stones and very fine mesh require more pressure to push the gas through them. 

It was pointed out earlier that the best clean for hydrocarbon contamination was SPM followed by APM. It was also shown that after an HP step another step Is required to remove residual particulate contamination, suggesting that the APM step should follow the HP step. 

May be quantified by the amount of light which passes through the container. Some pharmacopoeia tests require a certain level of light transmission to be achieved in order that particulate contamination can be checked. USP XXIII provides a useful test procedure for light transmission. 

This level would represent the as manufactured closure and as such was the accepted standard of presentation to the customer in the 1970s. It was accepted that in this state the closures required further processing, cleaning and lubrication with silicone oil by the pharmaceutical company before sterilisation. The closures in the as-supplied condition could be assumed to have moderate to high levels of microbial, pyrogen and particulate contamination. 

Clearly there are issues here that the pharmaceutical industry needs to address. Particles of the smaller sizes specilied for measurement in the Clean Room Standards are not of direct concern to particulate contamination issues facing manufacturers of sterile pharmaceuticals. Furthermore, it is the quality of clean room technology that is the factor of greatest importance to the pharmaceutical industry, of which the attainment of clean room classification is merely an indirect index. In these circumstances a major increase in the amount of testing required to claim compliance with a particular classification offers no benefit to the industry, and may indeed unnecessarily increase testing costs, downtime, etc. 

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