Some of the strangest cases in backflow have occurred in commercial kitchens. Unfortunately, these cases don’t receive the big headlines like the food poisoning incidents. But the potential health hazard to the customer is equally as great.
My experience has been that a lot depends on the plumbing contractor’s approach. If you take a hands-on approach, the commercial kitchen is normally immaculate. If you take a hands-off approach, there exists a potential for disaster. Let me start by saying that taking a hands-off approach does not necessarily result in a problem. In many instances, the commercial kitchen is just fine.
What approach you take has to do with the dealing you have with the kitchen appliance contractor. With most commercial kitchens, a separate contractor is hired to install the kitchen equipment. These contractors are specialists who only do commercial kitchens. Sometimes they are good, sometimes they are not. In most instances, the kitchen appliance contractors have a “take charge” attitude, controlling all of the construction aspects of the commercial kitchen. That’s not so bad if they are good.
No Experience: Quite often, the commercial kitchen contractor does not have any experience in the plumbing profession. They can connect pipe to their equipment, but beyond that, they are novices. They certainly do not receive the extensive training in backflow protection that a plumber receives. This is when you need to take a hands-on approach.
The kitchen equipment often does strange things with the water. If the water supply is properly isolated by backflow preventers, then they can do anything they want. It is somewhat out of your control after the backflow preventer.
The most common location of cross connections is the dish-washing equipment. Today, dishwashers have all sorts of connections. There is a pre-wash agent, a detergent, a glass rinse and a regular rinse. There may also be a heat exchanger to boost the water temperature. When you are installing the water supply to the dishwasher, the restaurant may not have signed an agreement with the company that supplies the detergents and rinse agents. Hence, it is recommended that you coordinate the installation of the detergents with the owner. Some of the more reputable equipment has built-in backflow protection. Companies that come to mind are Ecolab, Johnson Wax and 3M (listed in alphabetical order so as not to offend anyone.)
There are some manufacturers who believe they don’t need backflow protection. One manufacturer actually explained to me that their detergent dispenser works on a venturi principle. He summarized that if the flow was not in the direction of the venturi, you couldn’t contaminate the potable water. I, of course, laughed. I spent a considerable amount of time trying to explain backflow. When we were done, he claimed that he would add backflow protection to his equipment. I’m not sure he ever did.
With the heat exchanger on the dishwashers, they are often supplied with hot water or steam from the boiler. If the heat exchanger is a single-wall heat exchanger, that may create a problem with the plumbing codes. Some codes permit a single-wall heat exchanger provided there are no hazardous chemicals added to the boiler. One way around the connection is the installation of a backflow preventer.
While we are on the subject of steam in a commercial kitchen, there are bread ovens that spray steam onto the bread during the backing process. If you are providing the steam boiler for such an installation, there are very strict regulations by the Food and Drug Administration regarding the additives permitted in the boiler. I thought they were kidding when I heard that boiler additives have to be FDA-approved, but such additives exist.
The Most Scrutiny: The equipment coming under the most scrutiny are the carbonated beverage dispensers. If you are like most plumbing contractors, you leave a water supply sticking out of the wall. Somewhere in the piping is a shut-off valve. You would assume the beverage dispensers only have a dual valve. Just about every major plumbing code doesn’t recognize the dual check valve as an acceptable backflow preventer.
What you should be leaving at the wall is a connection that has a “backflow preventer with intermediate atmospheric vent” with stainless steel components (or other non-brass components) downstream of the second check. The common description of the valve is a Watts 9BD, however, there are other manufacturers of the valve besides Watts.
For other food service equipment having water connections, make sure the backflow preventer is suited of the intended service. I think commercial kitchens account for more atmospheric vacuum barkers per square foot than any other building location. If the atmospheric vacuum breaker works, then it is a fine backflow preventer. But if there is a shut-off valve downstream of the vacuum breaker, then you can’t use an atmospheric type. This is where the newer, spillproof vacuum breaker would be good.
Last, but not least, don’t forget the gooseneck faucets. If the faucets are on a spring return, most plumbing codes do not require any backflow protection. If they are not, a backflow preventer may be required. I say “may” because some of the gooseneck faucets are equipped with built-in backflow preventers. These are the type I prefer to have installed.
So here you thought that flipping burgers had little impact on the plumbing system. Keep a keen eye open the next time you are in a commercial kitchen. If a cross-connection jumps out at you, make sure you take care of it.