Condenser Water Piping Seminar

Two of the insurance industry’s biggest risk groups are builder’s risk and professional liability for architects and engineers.  Both of these groups are involved in the design and installation of HVAC as well as process cooling equipment.  We recently attended a seminar on the design and installation of condenser water piping.  The condensers that are referred to are large pieces of equipment that are used in conjunction with cooling towers and large tonnage refrigeration machines.  A number of problems can arise if the piping is not considered correctly.  For example, the life of a water circulating pump can be reduced dramatically if the friction loss through the piping exceeds the capability of the pump.  In addition, it is possible to introduce air into the suction line of the pump if the tower bypass is not done properly.  The net result will be flow instability.  Freeze protection can be another problem if not considered carefully.  In some applications, water is drained from the tower when subfreezing temperatures are expected.  But, if for some reason, water stays in a part of the piping and then freezes, the result will be a burst water pipe.  If the failure is not detected prior to start-up, then a large amount of water will escape from the system and clean-up can be become very costly, in addition to the piping repair.  These are the kinds of problems for which claims are filed and lawsuits can result. 

Advertisements

Vehicular Fire in Hayfield

The photograph below shows what can happen when a vehicle is driven through a hayfield.  Although the owner of the truck didn’t believe it could happen to him, he is now a firm believer.  The fire grew so quickly that the driver was lucky to get out of the truck as the flames were growing alongside the driver’s side door.  The fire occurred even though the ground was saturated after recent rain made the ground so soft that the truck got stuck in the mud.  While trying to extricate himself, the engine was heating the grass beneath the engine compartment.  Since the grass was already dry, it didn’t take long to ignite.  The only thing that kept the fire from spreading to the rest of the hayfield was the quick response of the fire department.  The heat that ignited the fire could also have come form the transmission and exhaust piping, including the catalytic converter.  If you have to drive through a field with tall, dry grass, don’t stop until you can get off the grass.  Be aware that stopping your vehicle over dry grass and allowing the engine to continue running can be just as bad as shutting down the engine while positioned over a tall patch of dry grass.  If you get stuck, get out of your vehicle, get away and then get help.      

Vehicular Fire in Hayfield

Wet Weather and Engine Damage

The recent rain storms in the southeast have been causing drivers a lot of trouble.  In addition to the flooding, the rain has been causing vehicle engines to stall.  It’s easy to see how water might be getting into engines and causing damage to pistons, rods, crankshafts, and bearings.  When such a claim is encountered, one of the first things to be done is to obtain an oil sample.  When water mixes with oil, the tendency is for the water to separate from the oil.  Water is naturally heavier.  Its density is 62.4 pounds per cubic foot.  Motor oil, on the other hand, has a density of approximately 55 pounds per cubic foot (depending on the weight of the oil).  After the sample has been obtained, if the oil appears to fill the entire occupied space, then no water most likely entered the engine.  However, if the oil appears to be “floating”, then water has most likely entered the engine.  Examples of oil in both states are shown below.

Uncontaminated motor oil sample

 

Motor oil suspended in water

WARNING:  if you know that your engine is about to fail and you are going to have to pay for a new engine, don’t try pouring water into the engine and claiming to your insurance carrier that it was flooded.  First, a wear metals analysis will indicate the condition of your engine.  Second, the vehicle better have been in a flood and even then, the entry point of the water into the engine will have to be established.  Third, the damage to the engine has to be consistent with that caused by water.

Watch Those Connections!

Some appliances such as stoves and dryers, do not come with line cords when the appliances are purchased.  As a result, consumers have to make separate purchases in order to use their new machines.  When attaching the cords to the appliance, pay close attention to the way the manufacturer requires that the line cords are connected.  For many do-it-your-selfers, this is no big deal.  It shouldn’t be a big deal for a professional electrician either.  However, we are all human and subject to making mistakes.  Case-in-point: the following dryer fire.  Although minor as residential fires go, the damage could have been much worse.  The photographs shown below illustrate how the manufacturer called for the installation of the line cord and the subsequent way, the cord was connected.

The manufacturer’s schematic drawing shows how the “hot” (red and black wires) lines of the line cord were to be attached to the L1 and L2 terminal block terminals.  The common line or white wire was to be connected to the N terminal on the terminal block.  Lastly, the green wire or earth ground, was to be connected directly to the appliance housing.  The photograph below shows how the white and black wires were reversed on the terminal block.

 

 

Since the common and earth ground points are electrically the same point, the dryer was, in effect, energized through the housing.  Anything in contact with the dryer housing, such as the exhaust duct, will also become energized.  Dryer ventilation ducts are usually coils of steel wire wrapped with a thin layer of vinyl or aluminum material.  As current flows through the steel wire, the external covering is heated.  If not stopped, the heat will cause the covering to melt and possibly ignite.

Wheel Separation in 2016 Ford Taurus-Possible Recall?

One of our recent investigations involved the separation of the left front wheel and whether it was the cause of a two vehicle accident.  The scenario was such that the driver made a right hand turn and felt the vehicle pull to the left.  The driver also stated that he lost control and hit a parked car.  Typically, in these types of impacts, the wheel is pushed into the wheel well.  But, in this case the wheel separated from the car.  Upon examination, it was determined that the threaded connection holding the strut to the frame was broken as well as the clamping part of the lower steering knuckle.  The failed parts are shown below.

DSC01046

Failed strut threaded connection

DSC01042Clamping part of lower steering knuckle found broken

It should be noted that the steering arm tie rod was also bent and broken and that a stabilizing rod connected to the strut was separated from its knuckle joint.  If either of these connections is broken, then the wheel will become unstable.  Are there other instances where drivers have experienced similar situations?  Is this a condition that warrants a recall?

Combined Heat and Power

I just completed a webinar refresher on combined heat and power systems.  If you don’t know or have never heard of a combined heat and power system just picture a jet engine that doesn’t move.  The heat coming out of the exhaust is used to make steam.  On the other end, the rotating fan is connected by shaft to a generator and produces power.  Another type of system uses a boiler to make steam.  The waste heat from the flue gas is reclaimed using a heat exchanger to make additional steam.  The primary steam is then routed to a turbine which in turn, turns a generator and makes electric power.  The secondary steam is sent to whatever process will utilize the steam, such as an absorption chiller, for air conditioning.  Most CHP systems are well suited for industrial applications where large quantities of steam and power are required. However, smaller systems are also made and suited for light commercial applications.  Advertised efficiencies run between 70 and 75% depending on manufacturer.  These machines are fairly reliable and so, in the course of my practice, I have only encountered one instance where a gas turbine (jet engine) failed to perform as required.  Two engines were installed in a university setting and used to provide steam and power to various campus buildings.  Shortly after installation, it was noted that one of the gas turbines was not performing as warranted by the manufacturer.  After review of the design of the entire system, it was determined that one of the gas turbines was not performing according to its design specifications. The claim was finally resolved when the manufacturer agreed to replace the machine with a new gas turbine.

Lathe Chuck Injury Due to Faulty Lathe Operation

One of the more interesting cases that we have been assigned had to do with a personal injury suffered as a result of an airborne chuck.  The injury occurred after an individual purchased a chuck and spindle adapter for use with a Shop Smith lathe that was manufactured back in the late 40s or early 50s (see photos below).

 

P1120708

Chuck and pin wrench used to tighten chuck onto spindle adapter

DSC00204

Antique Shop Smith Lathe

After attaching the spindle and mounting the chuck, the owner started the lathe and tested the operation.  Everything went well until the machine was turned off.  As soon as it was, the spindle shaft stopped but the chuck kept spinning and spun itself off the adapter.  The chuck went airborne, bounced off parts of the lathe and hit the owner’s hand causing severe injury.  The investigation came about as a result of the owner’s allegation of a defective product, ie, the chuck was defectively designed and had no means of stopping if it separated from the spindle adapter.  The chuck is designed to be tightened against the spindle adapter using special wrenches.  According to the owner, he claimed that he “tightened the chuck as tight as he could” before starting the lathe.  During the examination of the lathe, the lathe was started and run without the chuck attached.  When the lathe was turned off, it immediately became clear that there was something wrong when the spindle shaft did NOT coast to a stop.  It was also clear that the abrupt stop provided the torque necessary to cause the chuck to spin off the spindle adapter.  In addition, it was also noted that if the chuck was to stay attached to the spindle adapter, the torque applied during tightening had to be greater than the torque causing separation.  After working the math, it was determined that the owner could not have tightened the chuck was much as he claimed.  As a result, it was further determined that the owner unfortunately caused his own injury by ignoring the problem of abrupt stopping of the spindle shaft.  The lawsuit was subsequently dismissed.

%d bloggers like this: