SuperFlow AutoDyn, Operator'S Manual

Page: 203 / 208

Supplemental Information
Appendix A - Page 208
AppA General Testing Information.fm
A.10 Barometric Pressure
A very critical aspect of your dyno test procedure is barometric pressure readings. First, remember
that the barometric pressure figure with which you work must be the uncorrected barometric
pressure. This will be different than the relative barometer reading given by a weather station. You
must get the barometric pressure for the local altitude, temperature, and gravity.
SuperFlow dynamometer systems are equipped with a barometric pressure transducer and will
keep track of current barometric pressure conditions. However, just as you must calibrate the
torque system occasionally, you must also check and calibrate the barometric pressure
transducer. The first step is to obtain a valid barometric pressure reading.
If calling an airport or weather station for barometric pressure, be sure to ask them for an
“uncorrected station barometric pressure reading in inches of mercury.” Keep in mind, as a rule of
thumb, for every 1000 foot elevation above sea level, the barometric pressure will drop
approximately 1 inch of Mercury. So, if they give you a barometric pressure reading of 30.01 inHg,
and you are at an elevation of 2000 feet, they have given you the “relative” barometer and not the
actual station pressure. Ask again. The reading should be more like 28.01 inHg.
A better solution is to buy your own wall-mounted Mercury column barometer. Be sure to correct
the readings for temperature and gravity as described in the instructions included with the
barometer. There are several sources for these instruments. One good one is PRINCO
instruments. As of January, 2004, they can be located on the internet at
http://
www.princoinstruments.com/ .
A.11 Noise Interference
RFI (radio frequency interference) and EMI (electro-magnetic interference) are always a problem
with electronics around high output ignition systems and other high energy devices. Both can
occur simultaneously. The radiated energy from a high frequency section on a TIG welding
machine even can cause interference. The way we isolate our electronics and the way we suggest
for our customers to address the phenomena specifically apply to our equipment. We have had a
very good success at these applications and our customers typically work with all the various high
output ignitions, including the high energy, high frequency plasma units.
• Carefully separate all sensors and cables from close proximity with the ignition wires.
• Do not run a sensor cable parallel with an ignition wire.
• If a sensor must cross the path of an ignition wire, make it happen at 90deg if possible
(and with space between).
• You might want to explore putting a Faraday cage (device for shielding electronic
noise) around your ignition amplifier.
• The amplifier (ignition) case should probably be grounded (check with manufacturer of
ignition).