nPropyl Bromide DrySolv

Copyright 2008
Everett Childers
Tahlequah, OK

nPropyl Bromide DrySolv

DrySolv is a newer alternative solvent that is available for drycleaners to get out from under perc and its related rules, regulations, taxes, continually rising cost and general bad publicity.

The solvent is N-propyl-bromide and other names are bromomethylethane, 1-propyl bromide, 1-bromopropane and nPB according to Wikipidia, an online encyclopedia.  The trade name is DrySolv.  There is an antiseptic, or alcohol odor to the raw solvent that can be unpleasant when sniffed directly.  The boiling point is 160° F. and the viscosity index is 5.241 cP at 20 °C.  (68° F.) The MSDS states there is no flashpoint and it is heavier than water by about 1/3rd and it is not known to be a carcinogen.  With that said, there are some concerns about its future testing for toxicity and human health effects, the same as any other chemical or chemical compound.

It is a corrosive material the same as perchloroethylene is corrosive without inhibiters and stabilizers.  When we began utilizing fourth and fifth generation perc machines there began to be a lot of internal corrosion of the perc machines as some manufacturers of machines or chemicals promoted continuous distillation for solvent clarification.  The constant distillation would wear out the inhibitors and stabilizers resulting in a very corrosive chemical inside of a metal housing with water and heat added to the mixture. Many years ago I asked one of the perc chemical company’s technical representatives about the corrosiveness and stability of perc and was told that perc was a very stable product and stabilizers were not added to control corrosion.  It soon was made public that perc is very corrosive and stabilizers and inhibitors are added to the raw perc in order to use it in drycleaning machines.  DrySolv is also a corrosive chemical and has been stabilized but with proper distillation and drying temperatures it should not be a problem in a tight machine.

The DrySolv solvent was originally thought of as a “drop-in” replacement for perc after replacing gaskets and seals with those that were more resistant to degradation from the solvent and with some minor conversion necessary for a perc machine.

A Conversion Story

A drycleaner in Portland, Oregon, Brian Olson at 45th Ave. Cleaners was one drycleaner who converted his Permac machine for the use of DrySolv.  He was faced with the dilemma of an aging perc machine, higher taxes on perc and in an area where people tend to go along with any improvement that will be a bit more environmental, and felt a conversion would be a lot less costly than a new alternative machine.  He was also intrigued by the short cycle of approximately 28 minutes per load, its greater cleaning ability and gentleness to fabrics, dyes and trims.  The fact that he would not have to buy, use or dispose of filters was also a selling point for him while maintaining water clear solvent in which to clean clothes.  Brian was also happy to get out from under the dark cloud that surrounds perc.  His converted machine is delivering 1022 pounds per gallon on the high end and a minimum of 987 pounds cleaned per gallon solvent.  These numbers are impressive for anybody’s solvent.

Well over 100 machines are running with DrySolv in the United States. They range in sizes from 30 to 110 pound capacity. Brands being used are BowePermac, VIC, Marvel, Columbia , Firbimatic, Multimatic, Union, RealStar, TechnoDry USA, Hoffman/NY, Detrex, and Donini. The machine sizes are varied but the majority are 55 to 80 pound capacity units. They range in age from brand new to a 25 year old Multimatic.

At this time, only a few manufacturers will support their warranties when running DrySolv, two of which are Firbimatic and Multimatic.  Multimatic had a sign on their display machines at TEXCARE this year that read, “For Perc or DrySolv”.  TechnoDry USA has run DrySolv in Europe and configured their machines for cleaners in the U.S. and Hoffman/NY will warranty their machines with DrySolv.

Columbia and Union will not honor their warranties if anything other than PERC is used. Columbia is currently the only manufacturer found to have still doors made of cast aluminum, incompatible with DrySolv in the distillation process.  Retrofit doors are available from other sources.

At the California Convention recently in Long Beach the first DrySolv EDGE drycleaning machine was on display. A totally new machine designed and built in the U.S. by Dry Cleaning Technologies specifically for DrySolv solvent. The EDGE is an all electric machine that uses fewer Amps than traditional PERC machines. It promises to do a complete cycle in 20 to 24 minutes and have less than 200 ppm in the wheel when the cycle finishes. According to Dry Cleaning Technologies, the EDGE will be priced competitively with PERC machines.

When Brian’s drycleaning machine was originally converted and set-up Brian was given the following program to install, understanding that every machine is unique and he would adjust it as needed:

  • Fill time 1 minute; add 1 to 1.5 ounces of DrySolv D detergent per 10 lbs. of clothes.
  • Wash 5 minutes circulating through button trap. (No Filters)
  • Drain 30 Seconds to Still set at 10 pounds of steam pressure.
  • Extract 1 minute 30 seconds to Still.
  • Set dry time for 8 minutes at 110 F. and then go into auto-dry.
  • Cool down 7 minutes to about 85-90 F.

Brian has been in contact with other cleaners who have converted their machines to the use of DrySolv and received several emails from current satisfied users who stated that their experiences mirrored his and are very happy with their conversions.  He has also received emails from those who tried it, didn’t like it, and went back to perc.  Not one of them cited corrosion as an issue.  Poor solvent mileage was the problem and they decided to return to the use of perc.  (There has been one drycleaner who converted to DrySolv and has reported drastic corrosion problems to his drycleaning machine and surrounding metal)

In his converted BowePermac, the cast iron elbow leading into the condenser corroded, he reported, and the solvent is very corrosive to aluminum or cast iron still doors installed on a few machines but there are other doors that can be purchased to eliminate this problem

Actual cleaning results are quite satisfactory with very minimal dye bleeding and on the one occasion he had a dye bleed a simple re-cleaning eliminated the re-deposited dye.  It was an off white cotton/Spandex with an orange fabric on the inside of the coat at the sewn seams.  The orange bled and re-cleaning removed the fugitive dye.

Brian went on to say “There were two minor alterations to the machine; the pressure relief vent from the water separator was disconnected and then attached to the hose we used to fill the machine to run a “closed loop” from the separator to the button trap. DrySolv is much more volatile than PERC and by doing so we are reclaiming solvent that would otherwise be lost through the carbon filter. The last thing we did before running the machine was to close off the drain line from the water separator to the waste water treatment unit. This is done to help reduce vapor loss. A pair of vice-grip pliers made quick work of this and I simply drain the hose once a day and seal it off again.

Because DrySolv is volatile even just sitting in the machine, we found that the machine manufacturers start-up program, a short dry cycle, was inadequate to clear the wheel of vapor before the first run of the day. I now use the pre-programmed dry cycle which takes about 14 minutes as my “Good Morning” cycle. This works extremely well. We loaded the machine with clothes and started it. I have to admit, I was still nervous so I chose to run a dark load first. With a little experience behind me I am now comfortable running any classification of load as I need it. Going from dark to light creates no worries as I am using pure, fresh and distilled solvent in every load. This is particularly useful to get the larger loads out first and keep production going.

We made minor adjustments to the program I added and raised the steam pressure to the still so as to allow for the distillation to be complete by the end of the cycle. We also increased fill time and raised the drying temperature. Each machine will be somewhat different. The goal was to have the complete cycle finish in 30 to 35 minutes, which we easily accomplished. In addition, we added a second, shorter program for beaded and delicate fabrics. I could have done all the work required to convert this machine myself with just a little “tech support” over the phone to help guide and assure me that I was doing things correctly. It really was that easy.

The Edge Drycleaning Machine for DrySolv

The new Edge machine, designed for the use of DrySolv is being released first in a 75 lb capacity.  Smaller versions will follow.  It will do a complete cycle in about 20 minutes reducing the current 30 minute standard with DrySolv by 10 minutes.  The drum will have 200 ppm, or less, at the end of the cycle.  This is impossible to achieve with a conversion machine so it promises spectacular mileage.  It is also an all electric machine, so there is no drain on your boiler; it uses about half the amps of a perc machine and has an all new sub-zero heat pump.  It also has a simple 3 program microprocessor, regular clean, delicate clean and still maintenance.”

Brian Olson says “when I learned about the new Edge machine, I was immediately intrigued.  I found out about it after I was already using DrySolv and I really liked the idea.  It will be a couple of years before a machine the size I would need is in production and I have already ordered mine.  My Permac drycleaning machine will be 12 years old by then.  Will I suffer from corrosion issues before then?  Who knows?  I do know that I am not worried about it.  Any repair I have to make will be less expensive than the new machine I would have had to buy to get out from under perc.  I love the short cycles, reduced maintenance without the need for filters and crystal clear solvent EVERY load.  Most importantly, I love the fact that it is not perc and doesn’t have the baggage associated with it.  My customers are very happy about that!”

“I think DrySolv will be THE solvent that replaces perc in the future and many dry cleaners will be able to save their businesses by converting to it.  But then, maybe someone will come up with yet another alternative. Only time will tell.”

The manufacturer says its solvent works as well or better than PERC. I would counter that by saying it is far superior. I am cleaning everything in DrySolv that I was able to clean in PERC including beaded and trimmed garments. The faster run times have resulted in four loads cleaned in the same time I used to do three. The solvent itself, being stronger, does the cleaning work instead of relying on mechanical action resulting in little or no static or lint.. I have not needed to clean the button trap since I began using DrySolv. The lint filter itself is cleaned daily and only has a light layer of dust to remove. The shorter run times and lower drying temperatures also provide less distortion of the fabrics resulting in much faster finishing and I have been able to reduce pressing time by approximately one full hour a day and there is no odor what-so-ever in the finished clothes. Only a clean fresh scent is present. I have had no problems with redeposition of soils by not using filtration. There have been no issues with dye transfer or bleeding. Even in a dark load the white cotton linings in the waistbands of pants come out bright white. Of course the white loads come out bright and colors remain brilliant.”

DrySolv in the Marketplace

Brain said he always questioned the amount of waste generated while running PERC. “A great deal of it had to be coming from lint and with DrySolv I am generating a fraction of what I was before. With no need for filtration, the monitoring and maintenance of that component has also been removed. As far as spotting goes, it does an exceptional job on greasy food stains, mud and oils. Some prespotting is still required but has been greatly reduced. There is an increase in “sweet” spots due to lack of moisture in the system but with lower drying temperatures they are quick and easy to remove.”

“The conversion of a ten year old machine to a solvent it was never designed to use has not been without frustration and challenges. DrySolv is extremely volatile and even sitting dormant in the machine vapors will expand. This has resulted in a lot of extra work in making sure the machine is tight. Most of the gaskets only required minor tightening, a little at a time over a few weeks, and have held without a problem. Some have needed replacing. The materials of some of them soften from the vapors and may need to be replaced with viton gaskets. Once they are placed in the atmosphere they quickly dry and go back to their original form. The still gasket is viton and while I purchased an extra there has been no need to replace it. As well, the door gasket is holding fine but I have a spare on hand. I am reminded of co2 machines that need to change out the door gaskets every few loads. I did have to replace the still sight glass and condenser gaskets, but they were ten years old and in need. I also replaced the lint filter/button basket gasket. I think the design of the fitting will be a continual problem and will have a viton gasket made to replace the factory issue. Fortunately, my PERC leak detector works well with DrySolv and its easy to locate where the vapors are coming from. I consider the costs associated with gaskets just a part of the conversion and learning process.”

Brian went on to say “In order to answer the question, “Is DrySolv right for me?” I had to try it. It works better and faster than anything now on the market. It has reduced my labor in several areas and with increased solvent mileage is cost effective. Most important to me, it has no negative environmental history and that makes it easy to promote to my customers. DrySolv is not only right for me, but with its relatively small cost to convert a PERC machine may well be the answer so many PERC cleaners are looking for.”

Dry Cleaning Technologies, a division of Enviro Tech International Inc., produces the DrySolv Solvent.  ETI was formed in the early 90’s with the goal of creating a cleaning solvent that would replace existing environmentally hazardous solvents being used in the industrial degreasing market. Research led to the development of n- Propyl-Bromide, (NPB), as the desired solvent. An additive was developed to improve solvency, azeotropic performance and inhibit acidity. EnSolv Precision Cleaning Solvent was patented in 1995.
DrySolv evolved from EnSolv and is the only direct replacement currently on the market for PERC in class IV cleaning machines.

NPB has received EPA “SNAP” approval. The Significant New Alternatives Policy program has determined NPB possesses minimal Ozone Depletion Potential. In addition, NPB has been shown to possess minimal Global Warming potential. Based on low atmospheric reactivity data produced through independent labs, ETI has petitioned the US EPA for Volatile Organic Compound, (VOC), exempt status. The exemption petition is currently pending.

An update to the above article is that Brian is still using DrySolv in 2010 and is still pleased with its performance.