Still draining pipe systems?
Think again...
Avoiding lengthy shutdowns whilst being environmentally aware can save money and minimize inconvenience to building users
W
e often read and hear about the benefits of constructing and designing eco-friendly, green, LEEDengineered (Leadership in Energy & Environmental Design) sustainable buildings. These are the buzz words of modern construction development in North America today, but what about the maintenance of these structures? We know that upgrading that chiller or boiler is going to save us energy and dollars over the course of its lifespan, but what if those same savings are going to be gradually offset by poor maintenance practices? What if those same maintenance practices were also hazardous to the environment and caused major inconvenience to the building occupants? “Sustainable” no longer appears to be appropriate in this situation. Sustainable design and construction must be backed up by the equivalent approach to maintaining these systems in order to reap true long-term benefits.
A four-inch diameter shut-off valve has to be replaced on a chilled (air conditioning) water pipe at a downtown office building. In many cases, the initial response of the contractor is to drain the system. Depending on the size of the building, this may result in dumping hundreds or thousands of litres of water containing chemical corrosion inhibitors and/or glycol. The draining down alone can take several hours on a large system and overall downtime is extended further as latent heating or cooling dissipates from the building. This creates a time lag before the building can heat up or cool down again once the maintenance work is completed. Here we can identify a number of nonsustainable issues: wasting water; dumping chemicals into the sewer is hazardous to the environment; cost to replace chemicals; cost to refill and purge the system of air; time spent dealing with these issues and inconvenience to the building occupants due to extended system downtime. In addition, the process of draining down
can also be in contravention of city bylaws. In Vancouver, British Columbia ‘Sewer Use Bylaw No. 299’ governs the drainage of fluids to the city sewer system, (http://www.metrovancouver.org/boards/bylaws/Bylaws/ GVSDD_Bylaw_299.pdf ). In order to be compliant with these regulations, mechanical maintenance contractors must store and reuse, or dispose of this waste in an approved manner. Contraventions of this bylaw carry fines of up to $10,000 per incident. System downtime is extended as the heating or cooling within the building may be switched off for at least a day while the work is carried out. The costs and time to reheat or cool the building are higher once the work is complete, as due to the passage of time, any latent heating or cooling has been removed from the building. One modern and sustainable way to avoid all these problems is to use an industryproven technology pioneered in England in the 1970’s. Cryogenic pipe freezing enables a small section of pipe to be frozen quickly and safely. This acts as a temporary shut-off
Steel pipe is frozen on either side of the valves to enable replacement, without draining the AC system – Nitro Pipe Freeze, Vancouver 2014.
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Ops Talk • Spring 2016
