NEW STRENGTH FOR FIRE AND RESCUE EXTRICATIONS
BY FRED KNOWLES
Industrial fire and rescue companies can never have too much
power when it comes to extrication incidents. Plane crashes, train wrecks, and
large-scale production equipment accidents can tax the resources of even the
best-equipped organization.
Recognizing the need for reliable, smooth-running hydraulic
power for heavy-duty extrication, we set about developing a new pump design
especially for industrial fire and rescue applications. Our primary objective
was simultaneous multi-tool operation with high reliability.
Three factors were foremost in our thinking as we began the
work:
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1.
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Because reconfigured OEM pumps tend to fail in use or provide
limited power, rescue tool requirements would exclusively define design
standards. We wanted to overcome such limitations as hydraulic fluid failure
and unreliable pump pressure while providing a low-cost solution.
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2.
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Dependable, long-life operation would be an absolute
requirement. To meet this standard, the pump had to meet the following
specifications: effective oil filtration; efficient oil cooling for
continuous duty; multiple device operation; and extended hose runs to support
device operation remote from the pump.
Our specifications required overcoming hydraulic fluid
breakdown, which occurs regularly at high temperatures in heavy-duty
applications. Another requirement was the ability to operate three devices
simultaneously.
Military and civilian aircraft crashes and production facility
and construction accidents can place extraordinary demands on fire and rescue
personnel. We wanted to strengthen response capability while enhancing the
confidence of the rescue teams using our equipment.
Extended hose runs would give the tool operator added
flexibility and better protection from accidental fuel ignition. Also,
keeping the power source remote from the accident site shields victims from
destabilizing noises.
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3.
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Diesel would be the pump’s primary power source. This would
ensure safe, steady operation and a ready source for electric
power--invariably a requirement when lighting or smoke fans are needed at an
accident scene.
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DIESEL POWER ADVANTAGES
Diesel power has several advantages in fire and rescue applications.
It can draw on diesel vehicles` main fuel source, making it inherently safer
than gasoline engines in rescue situations in which high temperatures or
hazardous conditions are a factor. The ability to power up cabinet-mounted
diesel systems before arrival at the scene is another plus. With a system up
and tools attached, personnel can hit the ground running and perform
extrication without delay. Heavy-duty design in diesel engines supports
virtually nonstop operation and extended- duty cycles. Diesels also can operate
under temperature and climate extremes.
For a power source, we chose Westerbeke Diesel. This U.S.-based
company has a proven record in fire and rescue and mobile medical applications.
DEVELOPMENT CHALLENGES
Preliminary planning pointed to a positive outcome, but actual
development proved challenging. Deciding to go with diesel was straightforward,
but designing the pump was another matter. With no OEM supplier that came even
remotely close to meeting our requirements, we realized we had to build our own
device from the ground up.
The XRT Rescue Tool Power System (as it was later named) had to
be compact enough when combined with a Westerbeke generator to qualify as a
System 1 tool and capable of being upgraded in the field to qualify as a System
2 or 3 tools as funding or demand allows.
Operating efficiency was another factor: Sufficient diesel power
needed to be reserved for electric generation while maintaining simultaneous
operation of up to three hydraulic tools operating at 5,000; 10,000; or 10,500
psi.
To get a sense of the tradeoffs we faced, a single tool
operating at 10,500 psi subtracts 1.2 kilowatts from electric power
availability. At 5,000 psi, the loss is .75 kilowatt.
Although configuring a system with additional power-generating
capacity is an available option with the XRT, we needed to keep our eye on our
primary goal: to create a compact, multi-tool hydraulic power source with
accessory electric power at a price accessible to a majority of users.
Pump design requirements were extreme--the unit had to be highly
efficient, lightweight, compact, and modular. The final design was a
high-pressure pump with individual elements, the failure of which would not
affect the remaining pump elements operating other tools. The XRT`s power range
is from zero to 10,500 psi.
PUMP WITHIN A PUMP
The XRT features a "pump within a pump"--a
low-pressure system for each tool port that assists in opening and closing
individual tools. With a tool fully closed, its capacity is redirected back to
the XRT`s main reservoir.
Should a low-pressure pump element fail in the field, it is
automatically locked out of the general operating circuit. Open/close operating
speed is reduced when this function is assumed by high-pressure elements, while
high-pressure cutting or jacking is still maintained at full pressure.
As inferred earlier, both high- and low-pressure circuits within
the pump share a common hydraulic fluid reservoir, but both pumps discharge
separately into the common control block. The block has dedicated chambers--one
for each tool port--creating another layer of dependability for the XRT.
Experienced fire and rescue personnel know oil temperature is a
significant factor in pump operation and reliability. A dedicated fan/radiator
subsystem cools the oil in the XRT, and a temperature switch activates the fan
at 1107F. The air-intake housing directs air against the pump radiator, thus
providing a backup cooling system. An optional 300-watt oil heater is available
for use in cold climates that require system preheating for operational
readiness. A 10-micron, full-flow spin-on oil filter is built into the return
line to trap sand, dirt, and other debris that invariably enter the system when
tools are changed at the accident site.
LOOKING AHEAD
The XRT design's utility will be confirmed in the long term by
the lives it helps save; short-term results suggest we are on the right track.
Fire and rescue companies across the country have
responded favorably to the XRT. At this writing, a substantial OEM has entered
into negotiations to license the XRT design. We are able to produce the product
on demand with numerous installing distributors nationwide. Technical questions
are welcome. The XRT Rescue Tool Power System has ports for up to three tools.
FRED KNOWLES is vice president of XRT Power Systems a division
of Hansen Marine Engineering of Marblehead, Massachusetts.
http://xrtpowersystems.com/xrt-hydraulic-rescue-pumps/
As seen in the publication
Fire Engineering August, 1997
