NOVALYNX CORPORATION MODEL 110-WS-16BP BAROMETRIC PRESSURE SENSOR INSTRUCTION MANUAL

Transcription

1 NOVALYNX CORPORATION MODEL 110-WS-16BP BAROMETRIC PRESSURE SENSOR INSTRUCTION MANUAL REVISION DATE: OCT 2005

2 Receiving and Unpacking Carefully unpack all components and compare to the packing list. Notify NovaLynx Corporation immediately concerning any discrepancy. Inspect equipment to detect any damage that may have occurred during shipment. In the event of damage, any claim for loss must be filed immediately with the carrier by the consignee. Damages to equipment sent via Parcel Post or UPS require the consignee to contact NovaLynx Corporation for instructions. Returns If equipment is to be returned to the factory for any reason, call NovaLynx between 8:00 a.m. and 4:00 p.m. Pacific Time to request a Return Authorization Number (RA#). Include with the returned equipment a description of the problem and the name, address, and daytime phone number of the sender. Carefully pack the equipment to prevent damage or additional damage during the return shipment. Call NovaLynx for packing instructions in the case of delicate or sensitive items. If packing facilities are not available take the equipment to the nearest Post Office, UPS, or other freight service and obtain assistance with the packaging. Please write the RA# on the outside of the box. Warranty NovaLynx Corporation warrants that its products are free from defects in material and workmanship under normal use and service for a period of one year from the date of shipment from the factory. NovaLynx Corporation's obligations under this warranty are limited to, at NovaLynx's option: (i) replacing; or (ii) repairing; any product determined to be defective. In no case shall NovaLynx Corporation's liability exceed product's original purchase price. This warranty does not apply to any equipment that has been repaired or altered, except by NovaLynx Corporation, or that has been subjected to misuse, negligence, or accident. It is expressly agreed that this warranty will be in lieu of all warranties of fitness and in lieu of the warranty of merchantability. Address NovaLynx Corporation 4055 Grass Valley Highway, Suite 102 Auburn, CA Phone: (530) Fax: (530) nova@novalynx.com Website: Copyright by NovaLynx Corporation i

3 TABLE OF CONTENTS Section No. Page No. 1.0 INTRODUCTION SPECIFICATIONS INSTALLATION Cable Assignments MAINTENANCE APPENDIX 1 PRESSURE CONVERSION TABLE APPENDIX 2 ELEVATION CORRECTION TABLES Introduction Using the Tables ii

4 MODEL 110-WS-16BP EQUIPMENT CONFIGURATION AND IDENTIFICATION iii

5 1.0 INTRODUCTION NovaLynx Corporation Model 110-WS-16BP Barometric Pressure Sensor Instruction Manual Barometric pressure (BP) is sensed using a piezoresistive sensing element. This element responds to changes in barometric pressure with a corresponding change in resistance. This resistance is converted to a voltage from which the microprocessor (or another data processor) calculates the barometric pressure at the elevation where the barometer is located. Because barometric pressure varies with elevation, the BP sensor must be adjusted to read correctly for the elevation at which it is installed. This is done using the offset adjustment screw located on the side of the sensor. Instructions are provided in Section 3.0 of this manual. 2.0 SPECIFICATIONS Range: to in Hg (956.6 to mb) Measurement span: 2.50 in Hg (85 mb) Resolution: ± 0.01 in Hg or ± 0.3 mb Altitude offset: 0 to +10,000 feet, screwdriver adjustable Absolute Accuracy: 0.05 in Hg Input power: 10 to 18 Vdc Output voltage: 0 to 5 Vdc = 2.5 in Hg (85 mb) span 3.0 INSTALLATION The 110-WS-16BP has been designed for use with the 110-WS-16 Modular Weather Station. The sensor is designed to be mounted indoors. This arrangement assumes that the barometric pressure indoors and outdoors is equal. An 18" length of cable is provided. Connect the three wires of the BP sensor into the terminal strip on the WS-16 module. The barometric pressure sensor is set for sea level when it leaves the factory. Because pressure varies with elevation, the sensor must be adjusted to read correctly for the elevation at which it is installed. This is done using the offset adjustment screw located on the side of the sensor. To set the barometric pressure offset for sea level, you must first obtain a reliable barometric pressure for your location. This can be found by contacting the nearest 1

6 airport or weather service facility. The barometric pressure range is to inches of mercury (956.6 to millibars). Nominal barometric pressure is 29.6 inhg (1013 mb). Call up the WS-16 main menu on the display terminal by pressing "M" and "Enter." Press "2" for current observations. Then press "1" for observation display. While watching the display screen, slowly turn the offset adjustment screw. Clockwise will decrease the pressure reading. You may have to turn the adjustment screw 3 to 10 revolutions before the display starts to change. Turn the pot slowly in single turn increments, then wait for the screen to update, every five seconds. If the value is moving away from the correct value obtained above, turn the screw in the opposite direction. Continue turning the screw until the displayed value agrees with the value obtained from the airport or weather service. Note: 1 millibar (mb) is equal to 1 hectopascal (hpa). 3.1 Cable Assignments Function Color WS-16 Connection +12V Power Red +12V 0-5Vdc Signal Green A2 Ground Black GND 4.0 MAINTENANCE Check and determine that the BP sensor offset adjustment has not drifted. Compare the displayed BP value to the present one obtained from a local airport or weather service facility. If the values do not agree, adjust the offset screw as explained in Section

7 APPENDIX 1 PRESSURE CONVERSION TABLE 3

8 APPENDIX 2 ELEVATION CORRECTION TABLES Introduction Weather stations located at elevations above sea level often need adjustment to the barometer so that sea level pressure is the indicated value. Sometimes the information necessary making for the adjustment is unavailable or is difficult to obtain. This document provides tables that give the barometer corrections for various elevations. A brief discussion of the concept of pressure variations with elevation is also included. Using the Tables Barometer corrections to sea level pressure are most often associated with airports, television reports, or National Weather Service offices. These organizations give sea level reduced pressure readings. Some large organizations may have networks of weather stations spread over a large region to measure lateral variations in pressure such as those produced by weather fronts. It is not necessary for a barometer to be corrected to sea level in order for it to operate. The correction adjustment is simply a preference for the way that pressure is reported. Barometric pressure corrections can be obtained by contacting a local airport or National Weather Service weather station operator and requesting the current local reading. The barometer in question is then adjusted so that its reading matches that obtained from the airport or NWS. Some error will be introduced using this method of adjustment, increasing with distance since lateral pressure variations may increase with the horizontal distance from the reporting weather station. The tables provided with this document are based upon the United States Standard Atmosphere and can be used in situations where no reporting stations exist within the immediate area. The tables give the correction factor that is added to the barometric pressure reading for a given station elevation. The correction is given both in inches of mercury (inhg) and in millibars (mb). Values are indicated for elevations expressed in feet above sea level. For any station elevation, add the deviation from zero figure to the barometer s current barometric pressure reading. As an example, consider a barometer located at an elevation of 4550 feet with a current reading of inhg. Using the tables, a value of 4.60 inhg should be added to the reading. The barometer should be adjusted until it produces a reading of inhg to report the equivalent sea level pressure. The standard pressure figures indicate the calculated barometric pressure at each elevation based upon the United States Standard Atmosphere. Actual pressures typically vary by up to 1 inhg (34 mb), depending upon weather conditions, time of year, and time of day. The variation is seldom more than 2 inhg (68 mb) from the values given, even in a severe storm. These figures provide a method for checking a barometer s operation. A barometer that is located at an elevation of 1950 feet and is reporting a pressure of 860 mb has a calibration problem or is sitting in the eye of a super hurricane! 4

9 STANDARD PRESSURE VS. ELEVATION Feet and mb ( feet ) ( mb ) ( mb ) ( feet ) ( mb ) ( mb )

10 STANDARD PRESSURE VS. ELEVATION Feet and mb ( feet ) ( mb ) ( mb ) ( feet ) ( mb ) ( mb )

11 STANDARD PRESSURE VS. ELEVATION Feet and inhg ( feet ) ( inhg ) ( inhg ) ( feet ) ( inhg ) ( inhg )

12 STANDARD PRESSURE VS. ELEVATION Feet and inhg ( feet ) ( inhg ) ( inhg ) ( feet ) ( inhg ) ( inhg )