HVAC Planning for MRI System

When planning for an MRI suite, it is important to understand the substantial coordination requirements and other challenges associated with designing a HVAC system to support MRI equipment. Due to the unique and complex nature of these systems, and the critical space requirements associated with them, it is important to involve a HVAC engineer versed in the unique attributes of healthcare facilities to offer solutions for overcoming these obstacles.

Variations Among MRI Manufacturers and Models The specific MRI system selected for a project significantly impacts the design of the HVAC support system. Because there are specialized HVAC support systems for each MRI manufacturer, it is critical to select the MRI equipment vendor early in the project to make sure the system design meets the manufacturer’s requirements. Delays in selecting the MRI vendor can lead to coordination problems, change orders and project delays.

Cryogen Vent Piping Systems Cryogen vent piping systems are a critical component of MRI safety.  MRI systems carry the risk of a “quench” (or complete discharge of the liquid helium) caused by pressure rising in the vessel due to an operational malfunction. A cryogen vent piping system serves as an alternate emission solution to minimize the impacts of a potential “quench”.   MRI manufacturers specify different design criteria for various types of cryogen vent systems and they can vary for different models within the manufacturer’s product line. This means each cryogen vent system needs to be custom-designed for the particular MRI model being installed. When renovating an existing MRI suite, it is also important to re-evaluate the existing cryogen vent system to make sure it meets the new MRI system requirements.

Supplemental Exhaust System In the event that a cryogen vent system fails, cryogen could leak into the magnet room, pressurizing the space. This pressure must be relieved by an emergency exhaust fan so that staff and/or patients can safely evacuate the room.  

MRI Heat Rejection System MRI systems typically use a cryogen chiller/dry-cooler to remove heat and reject it to the outside air in order to cool the liquid helium. In order for this process to work effectively, the MRI chiller/dry-cooler must be precisely aligned with the MRI unit’s heat rejection requirements and indoor heat exchanger. For this reason, it is important for a HVAC engineer to design and coordinate the interconnecting piping between the water chiller/dry-cooler and the heat exchanger in the MRI suite.

Equipment Room Cooling An equipment room has higher heat gain and tight temperature and humidity requirements than other spaces within a healthcare facility. Typically, the central HVAC systems for the facility cannot meet these requirements. For these reasons, you should consider a dedicated specialized computer room air conditioner system for the equipment room.

Because of the unique attributes associated with MRI systems and the lack of industry standards and codes enforced for MRI system design, it is important to consult an experienced HVAC engineer to assist with your MRI suite design early in the planning process. If you are interested in learning more about how you can properly plan for your MRI suite, please contact Jon Slagel, PE 717-845-7654 or jbs@ba-inc.com.

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