ENGINEERING
equipment used for medical research. If you have something nearby like a railway or construction work, isolating this equipment properly might require something as sophisticated as a bespoke system of air springs.
n 2: The beauty is in the detail This leads to the next important point. If you’ve read this far, it will come as no surprise that the next key ingredient in a good specification is the level of detail. It sounds so simple, but it’s worth dwelling on why this is so important. Remember that the purpose of all this is to limit the risk to your project, and that the specification document needs to have a degree of finality about it. It cannot leave any questions unanswered, so you need sufficient detail. Of course, you don’t want detail for its
own sake. There is no point, for example, in specifying what colour paint should be used on an isolator, when the goal is to set out the correct engineering principles. However, that caveat aside, more detail is generally going to strengthen or tighten your specification. Let’s take an example to further
illustrate why this is so important. Let’s say acoustic hangers are specified for a project. The specification might require spring hangers which offer a natural frequency below 8 Hz. There are many products on the market that could tick this box, but not all of them are designed correctly. In this instance, additional detail might include the misalignment capability of the hanger. For example, with minimal misalignment capability, the rod will make contact with the bracket, creating a transmission path and an acoustic breach. If the specification did not include details about the necessary misalignment capability, the contractor might simply pick the cheapest hanger that can meet the natural frequency requirement, without realising that this product will inevitably fail to isolate sources of vibration.
Where, say, a medical or clinical research facility is close to a railway or construction work, isolating the equipment within it properly – the image shows an MRI scanner – might require something as sophisticated as a bespoke system of air springs.
n 3: Place the onus on the supplier The specification should include enough design features that the consultant can walk away and forget about it, knowing there is little risk to the project. However, there may be situations where if the supplier doesn’t request the right information, then there is the risk of the wrong type of product being specified. Ideally, the specification should be written so that the acoustic products will be fit for purpose, and of course not all products are designed the same. For example, you would not specify the same size acoustic hanger for a small pipe versus a much larger pipe. The supplier should be proactive, and ask questions about load requirements so that the specification can be met. Yet if a supplier were to simply pick larger hangers without caring about the outcome, the contractor is unlikely to know or understand the risks this might introduce. At this stage in the project, the
consultant who originally wrote the specification may no longer be involved.
So, how do you prevent scenarios like the one just described? A good supplier should be able to willingly supply documentation that shows evidence that the specification has been complied with.
Novel engineering challenges Hospitals and medical facilities can throw up novel engineering challenges. The presence of a helipad for landing emergency helicopters is one particularly challenging situation. In this instance, getting the specification right requires addressing a difficult, but fundamental question: what do you isolate? You could attempt to isolate each individual piece of equipment. However, this would potentially limit the space, and would require large inertial blocks in each sensitive area. An alternative solution would be to isolate the entire roof using spring mounts. When we faced a challenge like this
at the Karolinska Hospital in Stockholm, we opted for the second option. A specification for this type of solution would require sufficient detail. Simply specifying spring mounts would be insufficient, as these would need to be a bespoke design tailored to the specific types of vibration that a helicopter landing on a roof would generate. It would also be advisable to install springs that can tolerate variations in final weight.
With some equipment highly sensitive to vibration, contractors and consultants may be looking at vibration levels far below what is perceived by the human senses.
70 Health Estate Journal May 2022
Vibration-sensitive equipment Another conundrum that often arises for medical research institutes or healthcare facilities stems from equipment that is highly sensitive to vibration. Here we are talking about levels of vibration far below what is perceived by the human senses. Sometimes, even a high-quality bespoke spring mount will be insufficient. We were recently involved in a project at the Cardiff Innovation Campus where we were called upon to help isolate a large electron
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