Holdfast Training Services Trial Blog

Hello all. Just a quick update on my mechanical adventures in America. My sites at the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) are drawing to a close so I was asked to head down to military Medical Research camp known as Forest Glen to fill in a gap created by their resident Mechanical Engineer retiring. Forest Glen is home to the Walter Reed Army Institute of Research (WRAIR) and is located just north of Washington D.C. The distance from home is actually smaller but with D.C. traffic (rumor has it that it is intentionally bad so as to act as a deterrence to invading forces!?!) my commute time has increased.

WRAIR is the largest biomedical research facility administered by the U.S. Department of Defense (DoD). The task at WRAIR is to repair ten air handling units (AHU), three of which are located in the basement with the other seven located on the roof in three separate “penthouses”(see image 1). These AHUs supply a variety of rooms within WRAIR including everything from animal laboratories, patient observation areas that monitor brain injury, and sleep management, photo development rooms as well as offices.

Image 1: Three Penthouses located on roof

Due to the fact that constant clean air supply is key to the operation of these rooms disruption to the AHUs has to be kept to a minimum. “Repair” is a bit of a misnomer as it is more of a full renovation of the inside of the AHUs while keeping the outside shell. For this to work correctly temporary AHUs (see image 2) are located beside each AHU prior to the beginning or work. The temporary units are then connected to the system as close to the existing AHU as possible.

Image 2: Temporary AHU

The existing AHU is powered down at the last possible moment with the temporary AHU immediately kicking in so as to avoid disruption to the labs downstairs. To further avoid disruption this always takes place at around 0500 when no humans are in the building and the ambient temperature is naturally low.

The repair of the existing AHUs consists of effectively gutting the interior (see image 3), installing a  divide in the middle so as to allow maintenance of the AHU in future without the requirement for temporary units and then replacing the filters, the copper cooling elements (see image 4), humidifier, fans and mixing chamber.

Image 3: Gutted AHU

Image 4: Removed cooling coils

Currently we are on the 3rd AHU of 10 with roughly 2 months allocated to each unit. The project is currently ahead of schedule but due to the limited times the AHUs can be shut off or tested once completed any delay could easily devour the existing lead.