Health care plumbing system design
By John Clark, P.E.
Health care plumbing system design is done in hospitals, clinics and hydotherapy facilities. The first step in the design and selection of plumbing fixtures is to review with the client what has been the past facility standard and discuss any new requirements of the Americans with Disabilities Act (ADA) accessibility, as well as the current recommendations listed in the 2015 edition of “Guidelines for Design and Construction of Hospital and Health Care Facilities.”
The client discussion begins with what has been working well, what has been a problem, and what is new in the International Plumbing Codes and the latest American Institute of Architects (AIA) Design Guidelines. Client goals are often based on economics considering initial costs, maintenance costs, and replacement costs. After discussions with the client, vendors and professional plumbing society members, the basic sink is a good place to start the fixture selection for material, size, style type and faucet. The selections are broken down into good, better and best choices. Hand-washing stations are in the lobby area, patient’s restroom, patient’s room nurse’s station, surgical suite, clinic doctor’s examination room, on-site laboratory and hydrotherapy areas.
Basic hand-washing sinks
Tempered water is the best choice for hand-washing. The tempered water should be in the 110 F – 115 F range. Provide a tempering valve to control the mixing of 120 F water to arrive at the tempered water temperature. Many sinks today are using electric point of use electric water heaters under the sinks to provide the tempered water to all nearby faucets. These sinks are for use in the patient rooms and public restrooms. Have the architect call the hand-washing station a “sink” instead of a “lavatory.” A sink requires a 1½-inch trap, and a lavatory only requires a 1¼-inch trap. Trap size relates to drainage time, which is also relative to waste water drainage time, so size does make a difference in getting rid of the soap suds in the sinks.
Good: A vitreous china 20 by 18-inch wall sink with 4-inch wrist blade handles, a 5-inch spout with a laminar flow outlet and a grid strainer. The advantage is there is a continued use of standard wrist blade faucet parts. The disadvantage is two hands are needed to achieve mixed tempered water temperature. There is also no scald protection.
Better: A vitreous 20 by 18-inch wall sink with a single hole center single lever (minimum of 4 inches long), a 43/4 inch spout with laminar flow outlet and a grid strainer. The advantage is flow quantity and water temperature can be adjusted with one hand. The unit contains a high limit adjustable water temperature stop for scald protection.
Best: A vitreous china 20 by 18-inch wall sink with a touchless flow sensor, standard spout with laminar flow outlet, external water temperature adjustment and grid strainer. The advantage is this unit provides touchless operation. The disadvantage is the unit costs about 20 percent more than other faucet choices and needs battery maintenance.
Nurse's patient room service sinks
The sinks are generally counter sinks. These sinks can have the features described above, except they should have a goose neck spout, which should be about 10-inches high and have a 5-inch radius. The height allows clearance adequate to avoid contaminating utensils and the contents of carafes.
The 5-inch radius reduces splashing on the back ledge of sinks. Avoid the use of black counter tops because they show water splash marks. A rose spray outlet is also acceptable, instead of the laminar flow unit. For infection control, soft flow outlets are not allowed in the sinks.
Surgical hands-free scrub sink
The sinks are generally stainless steel. However, other sanitary alloys are available. The scrub sinks are designed to operate hands free water and soap control. The spout is goose neck with a non-aerating rose spray.
Knee water and soap control is the basic choice. However, infrared sensor water control is an option. The infrared sensors sometimes are bothered by direct room light into the sensor from refection off the sinks stainless steel finish. The refection problem leads to not using this choice. Single and multiple units are available.
The units should be an elongated comfort height bowl with a 1.6 gpm siphon jet flush. High-efficiency units are available using a 1.28 gpf rate. Wall-hung units can be used for ease of cleaning. The wall-hung units should have a floor-mounted closet carrier that has three or four bolt anchors into the floor slab to prevent the fixture from pulling away from the wall. Most wall-hung units use a top spud for the exposed flush valve unit.
Rear spud units can be selected for concealed piping arrangements. Floor set units may also be used. Rear outlet floor set units are used in facilities with precast or post-tension slab construction. Note that rear outlet units require a higher water pressure to successfully flush the fixture, 35 psi versus 25 psi for normal units.
Bedpan washer lugs are available for a bed pan washer assembly or as a wall-mounted hose unit with a wall-mounted pedal valve. If a hose arrangement is selected, provide a wall-mounted vacuum breaker. The flush valve handle must be on the wide side of any ADA stall arrangement. The toilet seat should be white, open front, without a cover and have a standard commercial class stainless steel, self-sustaining check hinge.
Hospital patient rooms
The patient room requires a hand-washing sink and toilet in the restroom. The restroom should be similar as in a patient's home. A service sink for the medical staff use is in the bed space. An option is a combination unit provided in the bed space that integrates a toilet and a handwashing/clinic class sink can be used by the patient and the staff.
Clinic/laboratory work sinks
A self-rimming unit that is 22 by 19-1/2 by 7-1/2-inch single compartment, 18 gauge, 304 stainless steel is a common choice. A 22 by 19-1/2 by 10-inch unit is also available for washing larger pieces of equipment. The front to rear 19-1/2 dimension fits within most casework countertops. If a double compartment sink is required, select a 33 by 19-1/2 by 7-1/2-unit unit for standard use.
Faucet trim must include a goose neck with a laminar flow outlet. The goose neck for single compartment sinks can be rigidly connected in the center of the sink. The goose neck for the two compartment units must be a swivel type. The faucet blades are now referred to as elbow units and must be 6 inches long. The single lever units must also have a 6-inch long lever. The drain is a basket strainer type.
For a touchless configuration, a single casework foot pedal or a wall mounted foot pedal control can be used. If using a wall-mounted foot valve, mount the unit on a wall bracket so that the pedal is out far enough to reach from below the countertop. The faucet handle is used only to adjust the flow quantity and temperature.
Flushing rim service sinks
Flushing rim sink fixtures are available in wall-mounted (25 by 20-inch) or floor-mounted (27 by 20-inch types. The front and sides of the rim have stainless steel rim guards. The flushometer mechanism is mounted above the hose end spout, with elbow blade handles on the faucet trim. The flushometer activation may either be a handle washer or a sensor operation.
A bedpan washer is available as part of the flush assembly or as a wall-mounted hose end unit with a wall-mounted pedal valve. A laminar flow outlet should be provided rather than a hose end thread, which would require a hose and an atmospheric vacuum breaker.
Safety eyewash units
These units are usually mounted on the countertop or adjacent to a wall sink. The units are activated by a squeeze handle. A tempered water supply must be provided to the hose connection. The tempered water supply can be from a safety tempered valve or from a 15-minute storage tank nearby.
Instrument-cleaning work stations
A countertop instrument-cleaning unit requires a supply of 140 F hot water for thermal sanitation. The units do not use much water; therefore the 140 F water source must be immediate.
The solution is to provide a point of use hot water heater below the countertop. The water heater may be in the base cabinet. Select a unit that does not have a pressure and temperature (P&T) relief valve, because units with a P&T valve will require a floor drain to accept the relief from the valve.
Hydrotherapy whirlpool tanks
These units require a fill system, drain system and spillage drain. The fill system and drain system should be sized as large as possible to reduce the turnaround time required to fill, drain and clean.
Time is money in the health care industry. The spillage drain should have a deep seal trap, a trap primer or a trap assembly to minimize the problem of the trap drying out, which creates odors.
These units use a thermostatic mixing valve with a wall-mounted thermometer to show the mixed supply water temperature.
It was discovered that the refillable liquid soap systems were becoming contaminated. Therefore all soap systems in the health care market have gone to disposable foam soap containers. These units also minimize liquid soap from dripping onto the counters and floors.
Cross flow between hot and cold service lines
Verify that every mixing faucet has an integral check valve or that check valves have been added to the service lines. A common problem faucet is one with hose end outlets, often used in mop sinks and flushing rim service sinks.
This article notes many little things that make the difference between good design and what was always done in the past. To get the feeling of the real value of wrist blades, single-handle lever faucets and sensor faucets, have a conversation with the health care infection control staff of your client.Also, tempered water use is a growing trend for hand-washing. Even though, over 50 years ago our design team was directed by a major multi-state medical group to provide tempered water for all hand-washing sinks.
John A. Clark, P.E., is a retired senior management MEP engineer with over 50 years of experience with commercial, health care and industrial projects. He has authored many articles and papers on plumbing, fire protection and HVAC.