Destructive Force of Ice

As most everyone knows, this winter has been hard on just about every corner of the country.  It’s been a very cold winter and the southeast has had its share of low temperatures.  For this reason, buildings that must be protected against fire sometimes have to use dry sprinkler systems.  Conventional systems that pressurize lines with water up to the sprinkler heads are impractical because the lines are usually routed through areas (such as attics) that are subject to falling below freezing.  As a result, the water in the lines can freeze and cause the lines to beak or burst.  When thawing occurs, water damage will also occur.  In order to prevent such damage, dry systems are employed.  That is, instead of filing the lines with water, the lines are pressurized with air.  Pressurized air serves to keep the main water valve closed until such time as a fire causes the sprinkler heads to open and relieve the pressure.  As the air pressure is relieved, the main water valve opens, water fills the lines, and exits through the open sprinkler heads to fight the fire.  However, there are times when water can get into the branch lines.  Water can enter when there is a loss of air pressure due to a leak in the system or when water is completely removed such as after a hydrostatic test.  The photos below show what happens to an iron pipe tee when water is frozen inside.  In one instance, the tee is broken in half whereas in the second instance, the tee is fractured on one end.  Note that both fittings came from the same job.  Ice typically expands between 9 and 12% by volume and as a result, places a tremendous amount of pressure on the fitting walls to cause failure.


Air Conditioning in the Winter?

Whoever heard of air conditioning in the winter?  It’s cold outside and you need warm air, not cold to be comfortable, right? That certainly sounds reasonable.  After all, most people are using their furnaces at this time of  the year.  You might not be aware of it but, it is possible to create enough heat enough within an enclosure so as to require cooling instead of heating.  Most homes lose heat at a faster rate than can be replaced by supplemental sources (ovens, televisions, dryers, etc). As a result, some type of heating system has to be implemented in order to keep cold weather at bay.  However, in some office buildings, for example, the number of people and machines can easily produce enough heat to require space cooling in order to keep people comfortable.   Consider for example a 40 watt flourescent light bulb.  For each watt of power, the bulb produces 3.41 BTU/hr or 136.4 BTU/hr/bulb.  Most light fixtures are equipped with four bulbs. So, each fixture produces 545.6 BTU/hr. Imagine an office space equipped with 100 light fixtures. The total heat produced by all of  these fixtures is now at 54, 560 BTU/hr.  In terms of cooling, 1 ton of cooling is equal to 12,000 BTU/hr. The lights will require a cooling capacity of 4.5 tons. This doesn’t sound like  much but, when you start adding in other loads like people and computers, the heat output can be significant.

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