Many junior plumbing engineers I’ve mentored have been intimidated by medical gas design. On some level, I can appreciate their concerns, as medical gases are, in many cases, life safety systems. However, I’m also quick to remind them, as a former mentor did to me, that while medical gases are hugely important systems, designing them isn’t rocket science.

In fact, designing medical gas systems often follows a very methodical process that can be repeated across many project types with great success.

Perhaps the most important part of the medical gas design process is the first stage: discovery. This stage is where the engineer determines the project requirements by studying existing drawings, conditions and consulting architectural and client resources. 

While there can be many different pieces of information to study and absorb in discovery, I’ve found five to be consistently paramount.

Identify your resources

The very first thing you should do in the medical gas discovery process is identify what and who your resources are. Gathering information on existing conditions and remodeling projects is paramount to executing a successful design; getting copies of the most recent drawings — as-builts if available — is key to this. 

However, anyone who has worked on healthcare projects knows that these buildings get remodeled and updated frequently, and it is not uncommon that the owner’s system record drawings are not kept current. 

Therefore, you may need to supplement these drawings by creating your own resources — site surveys, photos of existing conditions and equipment, equipment maintenance logs, gas consumption, time of equipment service life and 3D scans of above-ceiling piping. These are all tools you may need to leverage to inform your design and avoid conflicts later. Some or all these resources might be needed to determine the capacity of existing systems and to determine how much additional load they can accept. 

As useful as the “what” resources are in the discovery process, I’ve found that the “who” resources can be at least as, and often more, helpful. The “who” resources can be users of the medical gas systems — physicians, nurses and other medical professionals who can give you insights as to how they work, what equipment they’ll be connecting to the systems, what procedures they’ll be performing with them and what levels of sedation they’ll be performing in given spaces. 

In efforts to understand this, I’ve often pushed architects and project managers to be included in the user group meetings with these individuals. Staff who work in the facilities department can be even more valuable, especially in remodel projects, as they often have a better understanding of existing conditions than anyone else. 

Make sure you get access to these staff members, as the discovery process can often generate more questions than you had at the onset. If the facility has seen prior remodels, spend some time talking about these with facilities personnel who were there when they happened.

Source equipment technology

 Conversations with facilities personnel often (and should) lead to discussions about what manufacturers and equipment technology they are familiar with and prefer. Medical vacuum pumps and air compressors are available in several different technologies (scroll, reciprocating, tooth, liquid ring, dry noncontacting claw, etc.), all suited to different applications and facility sizes. 

Facilities personnel will often have strong opinions about which technologies are best, which are invariably tied to what is the easiest and least expensive for them to service. If several technology types are viable for your application, then the best choice can often be the one that facilities personnel are the most familiar with. If you must deviate from familiarity due to an application mismatch or otherwise, make sure they are aware of this early and understand the implications.

Occasionally, the client will not have an opinion on the source equipment technology and leave the decision to you. In this situation, it’s important not only to consider the best fit for the engineering application but also for the client’s maintenance resources. 

For example, rural hospitals are often strained for staff and will outsource any equipment maintenance to a technician certified by the manufacturer. In these cases, the best equipment choice can be the one that requires the least maintenance and has a nearby technician who can be on-site the same day it’s needed.

Understand outlet keystyles

Outlet keystyles are one of the biggest sources of confusion in medical gas for design professionals. Outlet keystyles are the physical connection type in the outlet that any connected equipment must be matched to. If these keystyles are not correctly identified and specified, the client’s medical equipment cannot be connected to them. 

Many designers incorrectly believe that individual manufacturers make their own proprietary keystyles and they only need to identify the manufacturer correctly. While this was the case in the past, most manufacturers now offer medical gas outlets in several industry-standard keystyles. While several others exist, the four most common are shown in Figure 1.

Getting clients to identify the keystyle they intend to use is critical. Do not assume that an existing facility uses the same keystyle for all equipment and gases (although the majority do); it may be necessary to use more than one to stay consistent with what the facility has. 

Equally critical is ensuring that keystyles are correctly chosen in the submittal process. While some keystyles have manufacturer names associated with them, calling them by their index names as shown in Figure 1 is much more accurate and leaves less room for ambiguity.

Monitoring and connectivity

In new facilities, design strategies around monitoring of alarm signals are fairly straightforward. With rare exception, most facilities nowadays want alarm signals tied back to their building management system (BMS) with assurance that trouble notifications will reach maintenance personnel immediately. 

Existing facilities can be more complicated, as they sometimes have products from multiple manufacturers. Monitoring signals and equipment are often unique to individual manufacturers and mixing them is usually fraught with problems. If faced with multiple manufacturers in an existing facility, keep the monitoring signals separate from one another or replace everything with one manufacturer if given the opportunity.

For new and existing facilities, consult maintenance personnel on what they want monitored. Signals monitored by the BMS often cost upwards of $1,000 a point, which can overwhelm small projects with tight budgets. Additionally, while you should always ask the question, maintenance personnel often want master alarm signals monitored by the BMS but are generally less concerned with those from area alarms.

Code compliance

Lastly, when you survey an existing facility, be on the lookout for system elements not up to code. Some system components in aging facilities fall out of compliance as code language evolves, while others that were once compliant occasionally get replaced with noncompliant ones in nonpermitted remodels. 

The most common example of the former are outlet quantities no longer meeting current requirements, as these have changed over the years with updates to building codes, architectural standards and the Facility Guidelines Institute requirements. Another is inadequate ventilation in gas manifold rooms; past versions of NFPA 99 (section 9.3.6) made the air change requirements easier to achieve with natural ventilation, but mechanical exhaust is now often a more practical solution. 

When evaluating what system elements need to be brought up to code, consider which systems and areas the scope touches and keep in mind that verifiers can have different interpretations of what is fair game. A common interpretation is to identify the existing valve that will isolate the new work from the old and then require anything on the new work side in the system to be brought up to code.

While projects may require other discovery phase exercises for success, these five are often the most critical. Beginning this phase early before a project ramps up is best, as errors and omissions here tend to be the most costly later. Engage the client early, be generous with your anticipated time budget, ask lots of questions and count on the answers to generate more questions. 

If you think you’re asking for too much information, you’re probably right on track.

Aaron Bock, PE, is a senior plumbing engineer at Eppstein Uhen Architects. He has been designing plumbing systems primarily for the healthcare industry for more than 17 years and has sat on several related national thought leadership groups. He is a past president and current vice president-legislative for the American Society of Plumbing Engineers’ Wisconsin chapter.