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.

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Rheem Water Heater Recall

On May 26, 2016 Rheem recalled approximately 50000 electric water heaters.  The problem with the appliances was that the temperature control could overheat resulting in a fire.  The recall applied to 40, 50 and 60 gallon units.  Recently, we encountered a water heater where a fire had occurred and caused damage to the upper control area including the circuit board that controls the water temperature. In this instance, damage was limited to the upper front of the appliance and the ceiling of the closet where the water heater had been installed.  However, if the fire had gone unnoticed, the fire would have spread to the remainder of the structure causing significant damage.  Water heaters involved in this recall are still in circulation.   Consumers are advised to contact Rheem if they have an appliance that should be replaced before a fire occurs.  A copy of the recall is shown below along with Rheem’s contact information.

 

Holiday Greetings

R.J. Hill Consulting would like to wish everyone a very

Happy Holiday Season!

 

How NOT to Install a Water Filter

We recently investigated the cause of failure of a water filtration unit that cracked and caused an extensive amount of water damage to residential dwelling.  During the course of the investigation, it was determined that a whole house water filter unit had been installed in a cabinet beneath the kitchen sink.  This location is perfectly acceptable as were the piping connections that were made to connect the unit to the cold water supply line.  However, when the upper and lower halves were assembled, the pieces were put together with pipe joint compound.  This is absolutely unnecessary and amounts to an improper installation.  The filtration unit comes with an O-ring that is intended to fit between the halves and seals any gaps while preventing water leakage.  Although the unit failed as a result of over pressurization,  the presence of pipe joint compound indicated that the filtration unit had been improperly maintained.  The failure of the unit is shown in the photographs below.

Continuing Education Update

We just completed a seminar on steam system design.  The course covered such topics as sizing steam valves, traps and pilot valve applications.  The course also covered piping distribution as well as load balancing.  Following accepted design practices is as important as correctly sizing the components that make up the system.  With more concern placed on the conservation of energy, the time when ignoring energy waste has come and gone.  More and more energy codes are being adopted by states in an effort to curtail energy waste.  Tennessee, for example, follows the International Energy Code.  As a result, architects and engineers can be held responsible for not following proper procedure as outlined in those energy codes.  More importantly, architects and engineers can be sued if their designs do not perform as building owners expect.  It then follows that insurance carriers that provide errors and omissions coverage for architects and engineers have to pay for designer’s mistakes.  Those of us that practice in forensic engineering will be looking for deviations from code requirements as well as accepted design practices.

 

 

The Problem With Oxygen Depletion Sensors…

The problem with oxygen depletion sensors is that they don’t sense oxygen.  Oxygen depletion sensors (ODS) are found on gas log appliances and are intended to shut the appliance off before the oxygen in a space falls to a dangerous level.  ODS sensors are thermocouples which produce a millivoltage when heated.  For this reason, the sensing end of an ODS sensor should be in contact with the pilot flame.  When operating properly, the flame heats the thermocouple which produces a millivoltage which in turn keeps the main gas valve open and allows gas to flow to the main burner.  When the flame cools as a result of low oxygen levels, the thermocouple or ODS fails to produce the necessary power to keep the main gas valve open and allows it to close, preventing gas flow and subsequent ignition.  The real problem however, is not low oxygen level, but the production and distribution of soot.  Anyone who has ever dealt with a soot damaged home knows how difficult the process can be to recover from the damage.  You see, appliances that burn with a yellow flame are already burning natural or propane gas incompletely.  That is, the carbon not consumed by the combustion process, will be visible and deposited as soot on clothing, furniture, draperies and appliances.   As a result, the ODS will NOT shut down the unit in time to prevent a soot production problem.  The lesson to be learned here is that even though your appliance has an ODS, don’t be fooled into thinking that you are protected.  Remember, if your appliance is designed to burn with a yellow flame, it is already producing soot.  Keep an eye on your fireplace insert, particularly if yours is unvented.  You will eventually see soot on the inside walls and if you see it there, it’s in the house!  The only way to prevent further damage is to quit using the gas logs set.

 

What’s Wrong With This Picture?

In a recent investigation of a crane outrigger failure, we were provided with some photographs of the incident by the insured company’s personnel.  At the time of the outrigger failure, the insured company was attempting to lift crawler tracks for attachment to a 120 ton crane using a 40 ton boom truck.  It was understood that the weight of the tracks was 26,300 pounds.  However, as soon as one track was lifted off the ground, the left rear outrigger buckled.  From all indications, the load was under the load limit capacity of the boom truck.  Upon reviewing the photos that were taken by the insured company, and specifically the area where the buckling occurred in zoom mode, it was noted that the outrigger failed at the point were it exits its storage enclosure.  Upon further inspection of the photograph, something very unusual was noted.  Can you tell what it is by looking at the picture below

Give up?  If you look to the left of the area where the outrigger buckled you will see that the rear end of the large crane is resting on a part of the bed of the boom truck.  In the original photograph provided by the insured company, the position of the large crane on the boom truck bed, is not obvious because it was taken at a distance of several feet away from both vehicles.  The question then arises as to whether the view could have been distorted because of the angle of the photographer as they took the photograph.  The answer is no.  As it turned out, the insured company also provided additional photographs which documented the position of the large crane on the bed and after it was completely removed.  Unfortunately, those photographs cannot be published because they can identify the insured company and therefore, constitute a privacy issue.  Suffice it to say that the partial load of the large crane was enough to cause the outrigger to buckle when combined with the track load of 26,300 pounds.

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