The Medical Industry
Medical Component Manufacturer
Uses Vertrel® for Precision
A small subcontractor for precision metal assemblies used in medical products selected MicroCare CCA as the best replacement for HCFC-141b.
Medical products demand a level of cleaning performance that exceeds almost any other application. Manufacturers worry about inorganic particulate, like metal fining, which could impair the operation of a device. They worry about organic contamination which could cause biological problems – light oils, grease, and fingerprints can carry all sorts of microscopic dangers. The electronics in these systems carry ionic contamination which must be removed. Water cleaning systems used early in the assembly process also generate potential problems with water spots, entrapped cleaning agents, and dry residues. To resolve all of these problems, a small medical subcontractor in Connecticut is keeping their customers happy by using MicroCare CCA as a final cleaning process after assembly.
This company had previously used CFCs for their cleaning process and over the years found it and their vapor degreaser system to be trouble-free. When the Montreal Protocol phased out the use of CFCs, the company migrated to HCFC-141b as an interim step. They used that solvent for about six years. When the E.P.A.’s regulations banned the use of HCFCs in vapor degreasers, they began to search for alternatives.
MicroCare CCA requires cleaning cycles of 2-8 minutes, with an average of 10-15 parts in the basket during each cycle.
While they have an aqueous system for some of their primary cleaning applications, they felt it was too large, slow and energy-intensive for use as their final cleaning process. In terms of solvents, they considered three main products: HCFC-225 from Japan, HFE solvents from 3M Corp. and HFC solvents from DuPont. All three products performed adequately, but in their mind MicroCare CCA came up the clear winner:
- The HCFC-225 solvent is an ozone-depleting material, with a phase-out dated mandated by the Montreal Protocol and the Clean Air Act. Top management did not want to specify in an new solvent only to have to repeat the job a few years down the road.
- The HFE products worked fine but were considerably more expensive than the MicroCare CCA, by about 30%.
- The HFC products from DuPont worked very well and were backed by DuPont’s 50 years of experience in solvent cleaning. Top management felt that their customers would be most comfortable knowing they were using cleaning products from the cleaning experts.
Overall, the company has been very pleased with the conversion to MicroCare CCA. They purchased a brand-new Branson vapor degreaser to run the HFC solvent processes, so the transition was made easy by using state-of-the-art cleaning technology.
All of their parts were then tested for a day immersed in the solvent and no compatibility problems were found (which is to be expected, as HCFC-141b is a very aggressive cleaner). All of their parts were then test-cleaned in the new solvent to confirm the programmed settings on the automatic hoist would deliver the cleaning each assembly required. A few assemblies required some adjustments to their cleaning cycle. Finally, all of their key customers were advised of the change, and as expected none had any problems or questions with the proposal.
The actual change-over took about four hours, as the company took the opportunity to boildown the sumps and clean the system thoroughly. System set-up was fast and predictable – a few thermostat changes were all that was required. In addition, the refrigeration system is now operating at all times, even at night and at weekends, to minimize stand-by losses. By lunchtime the new solvent was in the machine and parts were being cleaned.
At this point the customer is using the machine at about 50% of its maximum capacity. Solvent losses are averaging 2-3 quarts (3.5 liters) per week. Cleaning cycles vary from two minutes to eight minutes, depending upon the assemblies. Labor costs are trivial as the entire process is automated, which frees workers for more productive tasks.
The company expects to use about three drums of solvent annually, and return a substantial portion of that solvent to their vendor for recycling credit. While top management agrees that the cost of the cleaning process is higher than it was when they used HCFC-141b, in terms of each individual part the cleaning cost “is less than pennies,” according to the floor supervisor. “Everybody likes the new solvent,” she adds.
Cleaning Oxygen Lines and Systems
with Vertrel® Solvents
Vertrel® MCA has been approved by several manufacturers as the ideal cleaner for the maintenance of oxygen systems.
Oxygen system cleaning is a critical cleaning application with more demanding parameters than usual. Oxygen systems are critical subsystems in many industrial, analytical, laboratory, military, medical, space and aviation products. Such systems are highly sensitive to contamination. For example, particles left as a residue in an oxygen line may hinder the operation of valves, sensors and controls or otherwise cause excessive friction in moving parts. Friction causes heat and premature component wear; this may be a potential source of system failure.
Oxygen systems need to be cleaned at the point of use, such as within an aircraft system. However, systems used to manufacture and transport oxygen also need to be rigorously cleaned.
Oyxgen systems come in all shapes and sizes. Here is an example of a six-inch gate valve used in an oxygen processing facility. This product was cleaned with Vertrel® using an immersion and wiping process. Cleanliness then was verified under a UV light, as specified in the customer’s procedures.
Previously, the most widely accepted oxygen system cleaning solvent was CFC-113. The continuing escalation in prices for CFC-113 – plus the well-known environmental drawbacks – have made it an undesireable choice. This has forced most companies to search for alternatives.
Several companies also have introduced slow-drying hydrocarbon solvents for this task. However, low-vapor pressure solvents are inadequate to the task for two reasons: they are combustible, and they are slow-drying. It is impossible to guarantee that slow-drying solvents will not be trapped within the complex shapes of an oxygen system. These combustible residues may contribute to an explosive situation once pure oxygen is reintroduced into the system (combustible materials ignite more rapidly in an oxygen rich atmosphere). Even particles which are not normally combustible behave differently in an oxygen atmosphere and may develop a high potential for explosion. For example, some metals will burn in an oxygen atmosphere if an ignition source is available.
Vertrel® MCA has been tested and approved for oxygen system cleaning. It was found to have the optimal combination of handling, cleaning, safety, environmental and economic characteristics. The material is nonflammable, noncorrosive, and environmentally benign. This makes it ideally suited for oxygen service cleaning applications.
Typical System Components
Cleanliness requirements differ depending on (a) the type of surface coming in contact with the oxygen (fixed surfaces such as the insides of pipes, or moving surfaces such as valve gates) and (b) whether the oxygen is in the form of a liquid or a gas. Oxygen systems also demands the use of a solvent that is compatible with the wide variety of materials and elastomers used in such systems.
- Instrument valves
- Flow valve assemblies
- Pumps, compressors, and diaphragms
- Heat exchangers
- Cylinders and containment vessels
- Tubing, hoses and pipes
- Flow meters
- Safety relief valves
- Stainless steel
- Low carbon steel
- Threaded pipe
- Particulate matter
- Handling soils
- Hydrocarbon oils
- Water contaminants
Today, Vertrel® MCA is listed by the Compressed Gas Association in the official Directory of Cleaning Agents for Oxygen Service. Vertrel® MCA also meets the mechanical impact testing requirements for cleaning liquid oxygen systems, in accordance with NHB 8060.1C, Method 13A. (NASA Handbook 8060 for Mechanical Impact-Liquid and Gaseous Oxygen, Test 13).
Components may be cleaned by a variety of methods. The required degree of cleanliness defines the number of cleaning steps. Whichever method is selected, oxygen service components require a sequence of methods that allow for cleaning, rinsing and drying. The sequence applies to not only new and refurbished parts, but also to field maintenance cleaning. Vertrel® MCA can be used in any of the following cleaning methods to individually or sequentially define a suitable cleaning process:
1. Vapor Degreasing
This method uses the vapors of heated solvent to remove contaminants from intricate, irregular or hard-to-access locations. Spraying with vapor condensation is also used to further remove contaminants from surfaces. In a typical two-sump degreaser, components are rinsed in pure solvent condensate. Extra cleaning power is provided by ultrasonic energy to remove fine particulate. As the parts equilibrate to the temperature of the solvent vapor, condensation ceases. The parts are clean, dry, and safe to handle. This method typically combines all steps necessary for cleaning, rinsing and drying.
Easy access, flat surfaces may be cleaned with a solvent-moistened, lint-free cloth. Aerosol sprays are a convenient way to handle the solvent and apply it to the wipe. This method is used when surfaces are large and flat, and/or when other methods are impractical.
Flushing forces solvent through a closed system with a sufficient flow and pressure to remove residual contamination. This method is typically used as a final rinse, after a preliminary cleaning process and before drying. Some systems require a vacuum to be “pulled” on the system to ensure the total evaporation of any residual solvent.
In this method, components are submerged in solvent for a specified time to dissolve and lift surface contaminants. Solvent agitation and ultrasonic energy are often used to dislodge particles and break up difficult-to-remove soils. Spraying in glove box environments is also used. This method is often used for a first pass, preliminary cleaning process.