Frequently Asked Questions About Using Ozone for Commercial Laundry

Q: Will ozone work on colored linens?


 Absolutely. As an oxidizer, ozone could fade organic based dyes, but all of the linen we have come in contact with over the last 10 + years has had commercial dyes and the cold water wash typically translates in to less color fade.


Q: Will ozone hurt my laundry washers?


 Gas phase ozone is more aggressive than ozone that has been dissolved in water. Some systems (see direct vs. indirect below) inject ozone directly into the washers. On occasion this has resulted in damage to the washer itself. In fact, one major washing machine manufacturer has voided its warrantee when direct ozone systems are used. In fifteen years, there have been no reported instances of any damage to a washer from an indirect ozone laundry system.


Q: Will ozone hurt my linen?


 There were tests conducted many years ago by the Textile Rental Services Association (TRSA) that showed linen being severely weakened by ozone. This test was done by applying strong levels of ozone gas bubbled onto the linen simulating a “direct” inject aka bubble application. In contrast, our testing and field experience has shown an improvement in textile strength with indirect ozone compared to conventional hot water formulas. Some of our customers have even cut their linen replacement costs in half (20 to 30% reduction is more typical).


We have used ozone on the finest hospitality linens available with excellent results.


Q: Will I need to vent my washers?


On direct inject (bubble) ozone laundry systems where the ozone is introduced directly into the wash wheel, it may be necessary to vent the washers in order to prevent too much ozone in the laundry work area. This is not the case with indirect systems provided the un-dissolved ozone is properly degassed prior to entering the washer(s).


Q: What’s the difference between indirect and direct ozone systems?


 Indirect ozone laundry systems (dissolved ozone system) dissolve the ozone gas in the water prior to the water entering the washer(s). If properly designed, it also removes any un-dissolved ozone so that the washer is filled with dissolved ozonated water. This design allows the customer to verify that the system is operating properly and that appropriate ozone levels are maintained. It also easily facilitates large and small washers alike and allows one system to handle all the washers in a given laundry. It also applies micro-bubbles which increase surface area contact with the linen and minimizes off gas concerns.


 Direct inject (bubble) systems inject the ozone gas bubbles directly into the washer. These systems have been effective for smaller washers (50 lbs). The bubbles are larger and it becomes increasingly difficult to apply the appropriate levels of ozone as washer sizes increase. These systems do not have a mechanism for the operator to verify that the system is working properly or what level of ozone, if any, is being applied. These are typically applied as one system per washer.


Q: What are the maintenance requirements for the ozone system?


 Like most items in the laundry, the most important efforts are to keep the equipment dry and reasonably lint free. Laundries are a tough environment for ozone equipment and we have gone thru various vendors over the years to make sure components are rugged enough for long-term performance.


Q: What are the downsides of ozone?


 One downside of ozone is asking people to change what they are doing. Even the smallest changes can often be difficult to implement and see thru for the long-term. This can be overcome with adequate training up front as well as follow up training, but takes an open mind from laundry personnel and management support as well a pro-active chemical rep and an ozone laundry supplier committed to your long-term success.


 Another downside is making sure that someone will be around to support you for the long-term. Problems will come up. As often as not they are unrelated to the ozone, but since ozone is the new technology ozone gets blamed. Look for support that is well versed in general laundry expertise as well as ozone laundry. Over half of all ozone laundry systems ever installed by various ozone suppliers are no longer in operation which ultimately means the equipment did not deliver on its promise and a significant capital investment was squandered.


Q: What about ozone and personal clothes?


We have applied ozone in scores of healthcare applications where personal clothes are washed in cold ozone and have never had a report of any fading or damage to personal items. There are some fine cloth and dyes that could potentially be impacted by ozone, but these aren’t typically found in OPL applications.


Q: Someone told me they tried ozone and you could smell the ozone from outside the laundry.


If ozone smell is significant outside the laundry, the system either needs repair or was improperly designed to begin with.


Q: Ozone made my laundry smell like oranges!


 It used to be fairly common on ozone accounts to use citrus based detergents. That’s where the orange smell came from and can be eliminated by simply using a non-citrus detergent.


Q: Is there a minimum size for using ozone?


 While we have customers with as little as 80 rooms/beds, our target market is at least 100 rooms/beds and preferably 150 or 200 plus rooms/beds. Usually, the bigger the application the better the payback. We look to guarantee a payback of less than 18 months on energy savings alone.


Q: Is ozone dangerous?


 Virtually all of the chemicals used in your laundry are potentially dangerous and ozone should be given similar respect. Ozone is a very aggressive oxidant that if allowed to permeate a laundry room can cause headaches and/or nausea which can last 24 to 48 hours. Ozone has a distinctive odor and too much ozone in the laundry is readily noticeable. When properly applied, ozone will have a sweet freshening smell on the linen which is all but gone at the end of the drying process. Constantly watery eyes, headaches and/or queasiness (especially if present in two or more laundry workers) could indicate that ozone levels are too high. Extreme ozone levels are readily noticeable and are similar to a strong whiff of chlorine that is immediately evident in the sinuses. Responsible ozone companies design their systems to assure that ozone levels are well within OSHA standards. (see safety and MSDS for further info)


Q: I heard ozone turns white linen gray.


 We have learned that you need at least 0.5 ppm of ozone in the wash wheel to activate the laundry chemistry. Many older generation indirect (dissolved) ozone laundry systems struggled to maintain these levels, especially as the equipment aged. Direct inject (bubble) systems can have a difficult time delivering sufficient ozone in larger washers (larger than 50 to 60 pound washing capacity). Linen could also be grayed from improper chemical formulations (a common error is too much alkali). These are readily testable and correctable. We have scores of customers using white linen and cold ozone and getting the whitest results ever.


Q: How much ozone do I need?


 As discussed otherwise herein, you need at least 0.5 ppm. Our systems are designed to deliver 1 to 2 ppm with some applications in the 2 to 3 ppm range


Q: How long does an ozone system last?


You can expect a system life of twenty years or more. No Maintenence or spare parts for 15-20 years.


Q: How does ozone reduce drying times?


 There are several theories, but it’s not yet clear. One theory is that there is less chemical left in the linen with ozone resulting in higher water retention. Another attributes it to less hardness issues with a cold water wash. A more complex theory looks to the Brownian effect on water tension when ozone is present.


Q: How about disinfection with ozone and cold water?


 Over the years we were involved with getting special exceptions in CA, MN, KY, TN, ID and others in order to use cold ozone for certain healthcare applications. We provided the data that showed that at appropriate levels, ozone is an excellent disinfectant. In fact, ozone is one of the best disinfectants available. In some cases, this was backed up by further field data.


Q: Do you still need bleach if using ozone for laundry?


 Unless you are using very high levels of ozone which is typically not practical in OPL laundries, you will certainly need to use bleach in conjunction with the ozone. As previously noted, minimum levels of ozone are required to activate the bleach and it’s equally important to control ph levels in order to get bleach activation in cold water


Q: Do I still need hot water?


 Your sheets and towels (room linen) can be washed in all cold (ambient water). F& B and rags will typically still need at least some hot water. This is because the greases and oils need to reach their melting point which is usually 120°F or less. There are some ozone systems that use warm water for all the linen and are basically only serving to freshen the linen with an ozone smell at the final rinse.


Q: Chlorine or oxygen bleach?


 Chlorine bleach (sodium hypochlorite) is the more common approach. In some colored linen and hospital applications, oxygen bleach can be successfully substituted.


Q: Can ozone reduce my drying times?


 Like chemical savings, reduction in dryer times can often be overstated due to unnecessarily long drying times prior to the ozone application. That having been said, we have verified reduced drying times, especially in moderate to warm climates. In mountain states where the cold water can be in the 30’s, the water is simply too cold to produce dryer savings. Typical dryer time reductions run 10 to 30%.


Q: Can I cut my chemical costs in half?


 No. Ozone is an oxidizer that helps activate your traditional laundry chemistry. While it is a very powerful tool, it should be kept in perspective that we are applying it at 1 to 2 ppm. Chlorine is applied at 75 to 150 ppm. There are also the other roles of the laundry chemistry that serve to break down and remove soils, which, while ozone may be able to help with, ozone is unable to do on its own. It is feasible to reduce chemical costs nominally if sufficient levels of ozone are applied, but these are outside typical OPL applications.

There are potential savings in chemical costs from ozone, but these are typically due to too much product being used prior to ozone. Too much product is usually counterproductive to ozone and so these overages often need to be reduced to normal levels. Nonetheless, it would be fudging to claim that these are chemical savings due to ozone.




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