8 Do’s And Don’ts Of Mission Critical Plumbing
What to avoid and what to tackle.
Let’s face it, plumbing is an afterthought in most buildings — especially mission critical — where cooling and power take center stage. But, that’s a mistake. When it comes to data centers, plumbing is an essential support to every other critical system.
For one, mechanical systems rely heavily on plumbing water supply and drainage infrastructure in data centers to do their job efficiently. There’s also the challenge of locating and designing plumbing infrastructure to avoid, and protect, electrical systems and equipment. Consider these 8 Dos and Don’ts when designing mission critical plumbing systems.
1. Don’t let your data center fill up like a bathtub. Raised-floor data halls can fill up like a bathtub if proper drainage is not provided. For one, there are often 3-in. perforated holes in a raised data center floor to enable the cool air to rise into the space. In the event of a fire, sprinkler discharge, or a mechanical or plumbing system leak, the raised floor area would need to be drained. In multi-story data centers, sitting water in a raised floor could directly affect the data hall tenant below, and at the very least, will cabling and power systems routed underfoot. By providing floor drains, located to minimize piping runs on the floor below, with leak detection, water damage will be minimized and building operators will be notified to investigate the leak.
2. Do protect the building’s sanitary sewer from backups. In larger metropolitan areas, data center sanitary systems may be connected to combined public sewers (sewers conveying both storm and sewage). In order to protect the data center from back-ups during high-rainfall, the sanitary system is completely reliant on sewage ejectors or backwater valves as a means to protect the building.
Sewage ejectors are reliable, but costly, and not permitted by code when there is a means to drain the building by gravity. Work with the local authority having jurisdiction (AHJ) and explain the critical nature of the building. Because there’s no guarantee that the sewers will not have backups, which could cause tremendous damage to the building and its stored data, it is not that difficult to convince local authorities to permit sewage ejectors. When you do outfit the data hall and or other areas of the building with sewage ejectors, make sure you:
Size the ejector for the total load while also taking into account the effect a sprinkler discharge could have
Coordinate with structural, architectural, and electrical disciplines as they need to be on emergency power
Connect the ejector to the BMS to monitor its operation
Make sure the pump is provided with 2N redundancy
Oversize the gravity sewers the pump discharge is routed to in order to handle the load from both pumps
3. Do use solenoid valves with leak detection and water dams for your domestic water supply system. The use of electronic solenoid valves to respond to leak detection is gaining popularity, and can help wherever there is an unwanted water break. While it can be costly, employing solenoid valves can be very effective.
For example, when designing one mission critical control center in the Midwest, the owner of the 112,000-sq-ft facility was intent on not suspending water piping through the ceilings of the facility. In this case, the water supply and mechanical piping were routed under raised floors in the main corridors. But what if there was a leak or pipe rupture? To minimize damage, ESD coordinated with the architect to create water-proofed dams in the command center hallways. Going one step further, the pipes were controlled with solenoid valves connected to leak detection. The valves were programmed to automatically shut off should a leak be detected under the raised floor and send a signal to the control center’s building automation system (BAS) to notify the building. This gives the maintenance personnel a chance to survey the leak to determine its origin. Manual bypasses were also installed so that unaffected water systems could be restarted while the leak is being repaired.
4. Do use automatic electronic trap primers or trap seal devices to protect trap seals on floor drains. Some data center floor drains may receive little to no waste. The traps on these inactive drains will eventually dry out due to evaporation. Dry traps will result in gasses and odors being released out of the drainage system.
There are two types of devices to employ when protecting trap seals, and there are pros and cons to both:
An automatic electronic trap primer is a solenoid valve that distributes water to floor drain traps via a manifold and tubing system. It is controlled by a timer and at least once a day the valve opens and injects water into the drain to protect the trap. Since they need electricity, the automatic trap needs to be wired and programmed, and the primer tubes also need to be routed from the manifold to the floor drains. Things to consider: cost, power source hookup, connection to the BAS, tubing coordination and installation.
Trap seal devices are rubber inserts installed in the drain outlet or strainer throat. Gaining popularity for use in mechanical rooms, the rubber insert minimizes evaporation and, should it dry out, prevents gasses from leaking out. Maintenance workers typically like mechanical traps, as they’re not automated, are easier to work with, and more economical.
5. Do consider plumbing requirements for mechanical systems. Generally, when mechanical equipment is specified, it may have special plumbing requirements. If so, find out from the mechanical engineer: What water pressures are needed? Is treated water necessary? What are the drainage requirements? Where should drains be located? Are there condensate or clear-water wastes? Is make up water needed? What types of backflow protection is required? The answers will be more specific to the equipment than code.
6. Do separate waste. When coordinating utilities leaving the building, some jurisdictions require separate clear water and sanitary connections. Check with the local AHJ, specifically in the Northwest U.S., to see what is required. They may also offer industrial treated water (ITW) for non-potable usage. There is a cost benefit to doing this, as the data center may pay less for ITW than potable water. While the infrastructure may be more for additional incoming and outgoing systems the utility rates will often be less. Return on Investment (ROI) depends on the utility’s ITW rate.
7. Don’t route water atop data halls. As a rule of thumb, keep water away from anywhere there’s electricity. Typically, roof drainage is routed to gutters and scuppers along the perimeter of the building to avoid electrical areas. Coordination of hose bib locations on data center rooftops is also critical so as not to route water over a data hall full of servers. In colder climates non-freeze hydrants will be needed, and typical hydrants will require a drain connection. Some hydrants have a reservoir for drainage, but that may first need to be reviewed and approved by the local AHJ due to concerns about water contamination.
Today, many mission critical facilities are built with future expansion in mind. For this reason, be cognizant of where the plumbing is routed. Owner demands may change as well even before the project is completed, altering room functions. What was supposed to be a storage room may now become an electrical room, and re-routing the plumbing may be necessary. While electrical and mechanical designs drive mission critical facilities, the plumbing is directly affected. Be aware of potential changes and how they can affect every discipline.
8. Don’t forget about tomorrow. Take future use of the facility and site into consideration when building out and sizing plumbing infrastructure today, especially when it comes to domestic water booster pumps. If this is a site where there will be future data centers built out, make sure the necessary plumbing base building infrastructure is added now. Always include provisions for future booster pumps to ensure that there will be enough water pressure to serve the building for years to come.
For example, when designing an 800-ft-long data center in Virginia, water system calculations determined that there was enough pressure to serve hose bibs and mechanical humidifiers at the farthest end of the building on day one. However, should the building expand or the surrounding site fill with additional data centers, the demand for water will increase, and therefore likely decrease the water pressure at the ends of the building. When considering potential future needs, piping stubs and an allocation of space was provided for a future booster pump.
REMAINING BEHIND THE SCENES
Plumbing systems are more important than most building owners or operators realize. Designing them right from day one will ensure they can remain the out-of-sight, but fully functioning base building system for years to come.