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Operation and Calibration Manual
Manometer Users Manual
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MESA LABORATORIES, INC . 12100 W. 6th Ave . Lakewood, CO 80228 (303)-987-8000 Model COXIII Dual Pressure Monitor Operation and Calibration Manual
901120025 Rev. B Page 1 of 9
CONTENTS
Description Specifications Operation Instructions Cautions Calibration Instructions Warranty
Page 3 Page 4 Page 5 Page 6 Page 6 Page 9
901120025 Rev. B Page 2 of 9
DESCRIPTION
The Mesa Laboratories Model CDXIII Dual Pressure Monitor is a dual channel digital display gauge manometer which has been custom designed and manufactured to the specifications of Cobe Renal Care, Inc. and for use by Cobe Renal Care, Inc. with the Cobe CDXIII pressure transducers. No other use is intended. It measures and can display gauge pressure from each of two channels (left and right), and it computes and can display the difference in gauge pressure between the two channels. Self-contained and portable, it is powered by a rechargeable NiCd battery or external AC adapter, and may be attached to an IV pole. Designed exclusively for use with the Cobe Laboratories, Inc. model CDXIII disposable pressure transducers, which transducers are connected to special CDXIII transducer cables located on each side of the meter. Display functions are selected with a rotary switch on the right side of the meter, and a power on/off switch is located on the left side. Analog output signals are available from banana jacks on the upper rear panel, and are used to monitor the measured pressure from each channel and the differential pressure. All three signals are available simultaneously from the analog outputs. The analog outputs may be connected to a voltmeter, chart recorder, or computer A/D card. In addition to selecting the display function, the rotary selector switch is also used to activate a low pass filtering function, which stabilizes the signal from systems that contain pressure pulses, such as a system that employs a peristaltic pump. When the rotary switch is set to one of the three counterclockwise positions, the filter is activated and all three signals (left, right and difference) are filtered. When the switch is in one of the three clockwise positions, the filter is deactivated for all three signals.
901120025 Rev. B Page 3 of 9
SPECIFICATIONS
Measurement Range, Each Channel Accuracy, Each Channel Accuracy, Difference -600 rnmHg to +100 0 rnmHg +/- 1 % of reading, plus +/- 1 rnmHg +/- 0.1 % of reading, plus +/- 1 rnmHg Typical +/- 0.5 % of reading, plus +/- 1 rnmHg Maximum 1 rnmHg 1 mVDC/rnmHg Continuous 9 VDC 500 rnA AC Adapter 3.5 rom TR plug, tip positive 8.4 V 110 mAHr NiCd 7.0 V +/- 5 % 4 Hr Minimum, 6 Hr Typical 25°C +/- 5°C OoC to 45°C with battery installed -40°C to 70°C with battery and transducers removed 10 % to 95 % 5" X 4.5" X 2" 1 3 oz.
Display Resolution Analog Outputs Output Short Circuit Capability Power, External
Power, Internal Low Battery Indication Operation Time on fully charged battery Operating Temperature Range Storage Temperature Range
Humidity (noncondensing) Size Weight
901120025 Rev. B Page 4 of 9
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OPERATION INSTRUCTIONS
ZERO
Turn power on and verify that each channel reads 000 when the transducers are open to atmosphere. If they don't, the zero reading can be adjusted by inserting a small screwdriver or "pot tweaker" into the zero adjustment holes on each side of the meter. Use the LEFT, NOT FILTERED position of the selector switch for adjusting the zero for the left transducer, and the RIGHT, NOT FILTERED position for adjusting the zero for the right transducer. Changing the zero adjustment does not affect the overall gain or linearity accuracy of the meter. Turn power on and set selector switch to LEFT, NOT FILTERED for static measurements and calibration, or to LEFT, FILTERED for measurements of pUlsing pressures. Connect left transducer to system to be measured. Turn power on and set selector switch to RIGHT, NOT FILTERED for static measurements and calibration, or to RIGHT, FILTERED for measurements of pulsing pressures. Connect right transducer to system to be measured. Turn power on and set selector switch to DIFF, NOT FILTERED for static measurements and calibration, or to DIFF, FILTERED for measurements of pulsing pressures (NOTE: if the pulses are commonmode, the filtering function may not be necessary as the pulses will cancel out). Connect both transducers to system to be measured. Display will be right gauge pressure minus left gauge pressure (difference in pressure between the two transducers) . Analog outputs of 1 mV/mmHg are present at banana jacks on the rear of the meter. All three signals (LEFT, RIGHT, and DIFF) are always available whenever the meter is turned on. If the filter function is activated by using one of the three FILTERED rotary switch positions, the analog outputs will also be filtered. The outputs are intended to be used with an external voltmeter, chart recorder, or computer AID card. Shorting the outputs will cause no harm to the meter, but can cause the displayed pressure to be incorrect. The meter may be operated from either the internal battery or from the supplied Alc adapter (charger). The battery is charged whenever the charger is plugged in, whether the meter is turned on or not. Low battery is indicated by inverted display segments, so the meter can not be used when the battery is too low. If the display is completely blank with the power switch turned on, the battery may be completely dead. If this happens the battery may no longer be able to hold a full charge and may have to be replaced. When the display indicates a low battery, plug in the charger or turn the meter off. NiCd batteries slowly self-discharge even when they are not being used, so it is recommended to keep the meter plugged into the charger when it is not being used. 901120025 Rev. B Page 5 of 9
LEFT
RIGHT
DIFF
OUTPUTS
POWER
CARE
Clean with a soft cloth moistened with water, and if necessary a mild detergent. Avoid temperature extremes and shocks. Do not carry or suspend the meter by the transducer connectors. Do not allow liquid into the meter; be especially careful not to spill any foreign substances into the analog output banana jacks, the charger jack or the zero holes. Use only Cobe CDXIII pressure transducers. Replacing a transducer requires recalibration on that channel. Use only 8.4 Volt 7 cell NiCd batteries such as Mesa PiN 202110002. DO NOT USE ANY OTHER BATTERY CHEMISTRY THAN NiCd. Use of any other battery chemistry may cause permanent damage to the meter and will void the warranty. Use of the commonly available 7.2 Volt 6 cell NiCd batteries will result in reduced battery life and overcharging of the battery. Do not apply any external electrical power to the transducer inputs. They are designed to be connected exclusively to the Cobe CDXIII pressure transducers, which electrically are a resistive bridge. Applying external electrical power to the transducer inputs may cause permanent damage to the meter and will void the warranty. The meter is designed to accurately measure pressure from -600 nunHg to +1000 nunHg. Exceeding these pressures may damage the pressure transducers. Liquid in pressure monitor lines, transducer protectors, or the pressure transducers may result in inaccurate readings. Chemicals that are not compatible with the Cobe CDXIII pressure transducers may damage the transducers. As with all precision instruments, frequent calibration checks are recommended, however recalibration should only be required if a calibration check indicates that the meter is out of accuracy specifications or if a transducer has been changed.
CAUTIONS
CALIBRATION INSTRUCTIONS
Calibration requires an adjustable pressure/vacuum source capable of delivering stable pressures from -600 nunHg to +1000 nunHg, and an external pressure reference that is 3 to 5 times more accurate than the meter's specifications. A 4 1/2 digit multimeter to plug into the analog outputs will increase resolution by an order of magnitude and verify that the digital display is properly calibrated. Recalibration requires removing the top cover by removing the four screws from the underside of the bottom case. Access to the display board gain potentiometer and the pressure circuit linearity potentiometers also requires removing the display board from the two brass mounting standoffs by removing the two 2-56 hex nuts. 901120025 Rev. B Page 6 of 9
CIRCUIT OPERATION
There are two independent channels that amplify and scale the signal from each of the two transducers. Each channel has its own zero, gain, and linearity adjustment. The adjustment potentiometers are located on the same side of the circuit board as their corresponding transducer. The Cobe CDXIII pressure transducers are designed for operation from -50 mmHg to +300 mmHg, and when they are operated outside of that range they become nonlinear, so the circuit has a linearizing function to compensate for that response. Without the linearization circuitry, the meter would have too much gain at negative pressures, and not enough gain at positive pressures. The amount of non-linearity varies somewhat from one transducer to the next, so potentiometers are used to adjust the amount of compensation for optimum response. Besides linearizing each channel, there is a differential amplifier to compute the differential pressure between the two channels, and a two pole low pass filter for each channel, which is activated by the position of the rotary switch. A comparator checks the battery voltage and sends a signal to the display board to invert the display segments if the battery falls below 7 volts.
CALIBRATE DISPLAY BOARD
The display board is essentially a 3 1/2 digit voltmeter without any decimal points. One potentiometer on it controls the gain, so that it reads out in the same millivolts an external voltmeter reads from the analog outputs. The display board should automatically read 000 when zero volts are applied to it. 1. Turn the meter on and set the rotary switch to RIGHT, NOT FILTERED. Connect the external 4 1/4 digit voltmeter to the RIGHT analog output. Apply +1000 mmHg to the right the transducer and verify that the display matches millivolts on the voltmeter (it is not necessary for the meter to read the correct pressure here, just for the display board to agree with the voltmeter) . I f not, adjust the gain potentiometer on the display board until they agree. NOTE: There is some intrinsic gain error in the display board at negative voltages, and it is typical for the display to read about 1 millivolt less negative millivolts than a voltmeter at negative voltages.
CALIBRATE THE PRESSURE CIRCUITS
2. With the selector still set to RIGHT, NOT FILTERED, open the right transducer to atmospheric pressure. Adjust the zero potentiometer for a reading of 000. 901120025 Rev. B Page 7 of 9
3. Apply +500 mmHg to the right transducer. gain potentiometer for a reading of 500.
Adjust the
4. Apply -500 mmHg to the right transducer and adjust the zero potentiometer for a reading of -500. 5. Open the right transducer to atmospheric pressure and adjust the linearity potentiometer for a reading of 000. 6. Apply +500 mmHg to the right transducer and adjust the gain potentiometer for a reading between 500 and 502. 7. Apply +1000 mmHg to the right transducer and verify that the reading is between 995 and 1000. If it is not, repeat steps 4 and 5. 8. Recheck the readings at -500, 0, +500 and +1000 mmHg. Typical readings will be -497, 000, 502, and 997. The nonlinearity of the transducers becomes more pronounced at high pressures (+800 to +1000 mmHg), so if -500, 000 and +500 are calibrated exactly, +1000 may be too low. Similarly, if 000, +500 and +1000 are calibrated exactly, 500 may be too positive. Repeat steps 4 through 6 as necessary to minimize the errors at all four points. In all cases, it should be possible to get errors of less than 1/2% at all four points. 9. Repeat steps 2 through 8 for the left transducer with the rotary switch set to LEFT, NOT FILTERED. 10. Apply +1000 mmHg to the right transducer and -500 mmHg to the left transducer, set the rotary switch to DIFF, NOT FILTERED and verify a reading of 1500 +/- 5. 11. To check the low battery indication, disconnect the battery and connect an adjustable power supply to the battery clip. Lower the voltage and observe that the display segments invert at 7 volts +/-.35 (typical threshold is about 7.1 volts). 12. Reassemble the meter in reverse order as disassembly.
901120025 Rev. B Page 8 of 9
LIMITED WARRANTY
Mesa Laboratories, Inc. ("MESA") warrants that this equipment will, upon delivery by Mesa to Cobe in new condition, be free from defects in material and workmanship for 12 months after date of sale, provided the equipment is used and maintained as specified in the operator's manual supplied with this equipment. This warranty is void if (a) the equipment is used under other than normal use and maintenance conditions, (b) the equipment is modified or altered, unless the modification or alteration is expressly authorized by Mesa, (c) the equipment is subjected to abuse, misuse, neglect, electrical fault, or accident, (d) the equipment is repaired by someone other than Mesa or an authorized Mesa service representative, (e) the serial number or other identification is defaced or missing, or (f) the equipment is installed or used in combination, or in assembly with, products not supplied by Mesa and which are not compatible, or are of inferior quality, design or performance. Specifically excluded from this warranty are CDXIII pressure transducers and their cables, chargers and batteries. The sole obligation of Mesa under this warranty, or under any other legal obligation with respect to the equipment, is the repair or replacement by Mesa or its authorized service representative, with new or refurbished parts (at Mesa's option) of such defective or missing parts (excluding CDXIII transducers and cables) as are causing the malfunction. If Mesa does not replace or repair such parts, the end user's sole remedy shall be refund of the price charged by Mesa for such parts as are proven to be defective, and which are returned to Mesa within the warranty period and no later than 30 days after such malfunction, whichever first occurs. Under no circumstances shall the end-user or any user or dealer or other person be entitled to any direct, special, indirect, consequential, or exemplary damages, for breach of contract, tort or otherwise. Under no circumstances shall any such person be entitled to any sum greater than the purchase price paid for the item of equipment that is malfunctioning. To obtain service under this warranty, the end-user must bring the malfunction of the equipment to the attention of Mesa within the 12 month warranty period and no later than 30 days after such malfunction, whichever first occurs. Failure to do so within the prescribed time shall result in the end-user being not entitled to warranty service. THERE ARE NO OTHER WARRANTIES FROM MESA LABORATORIES, INC. WHICH EXTEND BEYOND THE FACE OF THIS WARRANTY. ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, AND FITNESS FOR USE, ARE EXCLUDED. No Mesa dealer nor any other person other than an officer of Mesa may extend or modify this warranty. No such modification or extension is effective unless it is in writing. 901120025 Rev. B Page 9 of 9