Special PDI Supplement: Sanitary Floor Drains
When I began my career in the plumbing industry at Jay R. Smith Mfg. Co., my daughter was only three years old. And like most children of Smith employees at one time or another, one day she asked me, "What is a floor drain, Daddy?" This awareness of floor drains was instilled in her at an early age through my employment, along with the reinforcement of the virtues of plumbing from her grandfather, a licensed master plumber. The desire comes naturally to these kids to look at floor drain grates, cleanout covers, hydrants and other plumbing and drainage products to see if they can figure out how they work. Knowing how and why something works is the key to specifying and installing the correct product for the right application.
For those of us employed in the plumbing field, the floor drain is an important component in the modern plumbing drainage system. Once installed, the floor drain performs a vital service indefinitely and usually without need for service or attention.
Many areas in our modern buildings require floor drains that must satisfy high sanitation requirements and still conform to the aesthetics of the building. The industry has developed a complete line of floor drains to meet those needs. The sanitation criteria for such areas mandate specific drains referred to as "sanitary floor drains" or "sanitary floor sinks."
To meet the sanitation criteria, there are sanitary floor drains/sinks available that feature the inside of the drain body coated (sanitized) with acid-resisting porcelain enamel. Some may ask if this treatment is really necessary. The answer is obvious when we consider the many cast iron enameled fixtures required in the plumbing industry. Would you consider a cast iron bathtub or lavatory that was painted with an enamel paint? Certainly not! Bathtubs and lavatories, by the nature of their use, require the permanent sanitary protection that acid-resisting porcelain enamel can provide.
During the very early years of what is called the "Modern Plumbing Era," a floor drain usually was nothing more than a hole in the floor. The main purpose of a floor drain was to conduct surface water away from the surrounding area. When needed, crude covers and grates were put over these holes to prevent sticks, trash and other debris from entering. This arrangement became inadequate as plumbing and building construction grew more sophisticated, driving the drain industry to design many refinements into floor drains.
Yet, despite the availability of a variety of functional floor drains, many installations still resort to the "hole in the floor" method. These types of installations ignore the contention that the floor drain coverage in specifications is critical, ensuring that the right drain is installed in the right place in every building. Increased recognition of the need for proper floor drain application will increase a building's functional efficiency and ensure the ultimate in appearance and sanitary safety.
The prime considerations that must be addressed when selecting a floor drain are:
- 1. Sanitation-Will it create any hazardous unsanitary condition or violate a plumbing code?
2. Performance and Safety-Will it safely do the job you want it to do? This pertains to flow and loading characteristics.
3. Aesthetic Considerations-Will it compliment the area where it is to be installed?
SanitationEach floor drain should be designed so that it conforms to existing plumbing code standards. The body must not have hidden crevices and pockets in which food particles and waste matter may lodge. A drain so designed will not encourage the build-up of vermin and offensive odors. The inside of the drain must be free from obstructions that may prevent self-scouring flow through the drain.
The drain body and top must be made of materials capable of withstanding the corrosiveness of the waste that will flow into it. In typical applications, the drain material should last the life of the building.
Performance and SafetyEvery floor drain must have a large enough outlet to carry away the anticipated volume of water that will flow into it.
A large top is required to ensure fast entrance of the surface water into the drain without causing water ponding in the area to be drained.
The grate selected must have enough top open (free) area for proper drainage, yet the size of the openings must not create a safety problem.
Safety is a component of performance that cannot be underestimated. Grates and covers must be strong enough to withstand the anticipated maximum load that will pass over them. The loading requirements of ASME Standard, A112.6.3-Floor & Trench Drains, paragraph 5, "Top Loading-Classification," should be followed when selecting a grate. The loading requirements are as follows:
- Light Duty-All Grates having a safe live load under 2,000 lbs. (900 kg).
- Medium Duty-All grates having a safe live load between 2,000 lbs. (900 kg) and 4,999 lbs. (2,250 kg).
- Heavy Duty-ll grates having a safe live load between 5,000 lbs. (2,250 kg) and 7,499 lbs. (3,375 kg).
- Extra Heavy Duty-All grates having a safe live load between 7,500 lbs. (3,375 kg) and 10,000 lbs. (4,500 kg).
What is a "live load"? Per paragraph 5.2.5 of the referenced standard, it states: "The maximum safe live load is computed by dividing the load at failure by two." The procedure is to place a 3.5-inch diameter platen in the center of the grate and apply hydraulic loading slowly to the platen until failure.
Each drain must have the proper internal variation (i.e., sediment bucket, etc.) to intercept or screen floating debris, peelings, sand, metal chips or any other miscellaneous solids that it may receive.
Aesthetic ConsiderationsThe part of the drain visible at the finished floor level should blend and harmonize with the surrounding area/finish. It should not detract from the attractiveness of a finished area and should provide a functional appearance in unfinished areas. This can be accomplished by properly selecting:
- 1. The configuration of the top (round, square, rectangular) to conform with the surrounding area;
2. The shape and layout pattern of the drainage openings in the grate;
3. The material that compliments surrounding trim, especially in finished areas; and
4. Top materials that have good resistance to corrosion and discoloration.
When a drain is required that meets all of these criteria, such as in a food preparation area, a sanitary floor drain/sink may be the ideal choice.
What is a Sanitary Floor Drain/Sink?Exactly what makes up a sanitary floor drain/sink? As previously stated, the major feature is its sanitary acid-resisting porcelain enamel interior coating. The drain bodies have a large radius and rounded interior corners, and they are void of the usual grate recess, pockets and crevices common to ordinary floor drains. The absence of recesses, crevices and pockets permits smooth, self-scouring flow through the drain and eliminates any possibility of dirt and food particles being lodged in the drain body.
The material of the top frame and grate is also important. Nickel bronze grates are recommended for all areas. Nickel bronze will not discolor, and its bright "silver" finish is maintained due to the polishing action of traffic passing over the grate. Cast iron grates with sanitary acid-resisting porcelain enamel coatings are available but should not be installed in areas subjected to foot or other traffic.
There are sanitary floor drains/sinks available with variations for specific job requirements. Models can be supplied with a flashing flange to provide seepage control and a secure anchor for the body in the concrete. They should always be specified for installation in above grade floors. When a waterproofing membrane is used, a flashing clamp device should always be specified. Models supplied without a flashing flange are suitable for installation at grade, where some seepage would not be a problem (Figures 1A and 1B).
Internal AccessoriesSanitary floor drain bodies have various internal body accessories that provide both utilitarian and protective functions.
Bottom strainers are recommended to intercept debris that may otherwise cause an eventual line stoppage. The dome type design of some of these strainers can prevent splashing and offers a large free area that provides for adequate drainage and prevents clogging (Figures 2A and 2B).
Sediment buckets are recommended where sediment, debris or other solids are anticipated. A slotted bucket can be used for normal service, while a ported mesh-lined bucket should be used in dairies and food processing plants, where smaller particles such as vegetable peelings, seeds, cherry pits, etc., are anticipated. (See Figures 3A, 3B, 4A and 4B.)
A sanitary floor drain/sink has many top variations adaptable for use as an indirect waste receptor or as a combined floor drain and indirect waste receptor. One of the most popular indirect waste receptor variations is the use of a funnel mounted on the top grate of the sanitary floor drain/sink. Both round and oval funnels are also available. (See Figures 7A and 7B.)
When a combined indirect waste and floor drain is required, 1/2, 3/4 or angle grates are available. Grates and solid covers with center holes are recommended where applicable. Solid gasketed covers should be used where future or intermittent use is anticipated. Stadiums and convention centers, subject to seasonal or periodic use, can employ the solid cover variation to good advantage. (See Figures 5A, 5B, 6A, 6B and 6C.)
Stainless steel sanitary floor drains/sinks in Type 304 or Type 316 are also available, and they offer sanitation, corrosion resistance, durability and longevity. All of the variations and material options discussed earlier are also applicable to stainless steel units. Besides the kitchen-food preparation areas, stainless steel sanitary floor drains/sinks are ideal for breweries, dairies, creameries and similar food processing applications.
In summary, the material and design features of sanitary floor drains/sinks make this type of drain mandatory for all installations where food handling or processing is performed. Sanitary floor drains/sinks offer complete sanitary protection, easy cleaning, maintenance and the ultimate in appearance.