Contents

Rain Collector (#7857 & 7857M)
- Note: Model number 7857 is factory-calibrated to take rain measurements in 0.01 inches. The metric version of the rain collector, number 7857M, comes factory-calibrated to take measurements in 0.2 mm.
  - Components
    - Please make sure you have all listed components before continuing.
  - Tools and Materials Needed
  - Rain Collector Internal Components
- Note: The rain collector is shipped with the 40 cable coiled and exiting through one of the cable slots. You may want to uncoil the cable and feed it down through the hole in the base behind the tipping spoon.
- Prepare the Rain Collector
  - 1. Remove the cone from the base by rotating the base until the latches on the cone line up with the latch openings in the base, then lifting the cone away from the base.
  - 2. Carefully cut and remove the plastic tie which holds the tipping spoons in place during shipping.
  - Optional: Insert the Metric Rain Adapter
  - Note: Inserting the metric rain adapter converts the rain collector to take measurements in 0.2 mm increments for each tip of the spoons. The console or Vantage Connect must be configured to 0.2 mm as well. See your console or Vantage Connect user gu...
    - 1. Find the metric adapter included in the hardware.
    - 2. Locate the magnet between silver-colored, V-shaped arms of the tipping spoons.
    - 3. Open the arms slightly with one hand while pulling the magnet out with the other.
    - 4. Separate an end cap from one end of the magnet.
    - 5. Slide the magnet, exposed end of magnet first, into the open slot of the metric adapter.
    - 6. Insert the metric adapter and magnet between the arms of the spoons, with the top (solid side) of the metric adapter facing up.
    - Test the Rain Collector
      - 1. Open the transmitter shelter on the ISS. Remove the foam insert and feed the rain collector cable up through the opening. Plug the cable to the appropriate connector in the sensor interface (See illustration on page 6.)
      - 2. Press the RAINDAY button on your console to display rainfall.
      - 3. While watching the display on your console to see if it changes, slowly tip the bucket until it drops to the opposite side. Each tip indicates 0.01" or 0.2 mm of rain. (It may take up to a minute for the first tip to register at the console.) If t...
- Installing the Rain Collector
  - Choosing a Location for the Rain Collector
  - Note: Climbing on your roof may be hazardous. If you are uneasy about installing your unit please have a qualified professional complete the installation. Davis specifically disclaims any liability for injury or loss resulting from the installation o...
- Installing the Rain Collector on a Post or Flat Surface
  - 1. With a 3/16" (5 mm) drill bit, drill two holes approximately 21/8" (54 mm) apart. Use the metal backing plate as a guide when marking the holes and a carpenters level to ensure the holes are level.
  - 2. Remove the rain collector cone if it is installed.
  - 3. Insert the 1/4" x 3" lag screws through the metal backing plate and the holes in the mounting base into the post. Make sure the base is level by checking the built-in bubble level.
  - 4. Tighten the lag screws using an adjustable wrench or 7/16" wrench.
- Installing the Rain Collector on a Pole
  - Accessories for Pole Mounting
  - General Guidelines for Installing on a Pole
    - 1. While holding the mounting base against the pole, place the two ends of a U-bolt around the pole and through the two holes in the base.
    - 2. Slide the metal backing plate over the bolt ends as they stick out toward the rain collector cone. Secure the backing plate with a washer, a lock washer, and a hex nut on each of the bolt ends. Adjust the height of the rain collector, then tighten...
- Finishing Steps
  - 1. Open the transmitter shelter on the ISS. Remove the foam insert and feed the rain collector cable up through the opening. Plug the cable to the appropriate receptacle in the transmitter. Replace the foam and close the shelter.
  - 2. To be certain the rain collector is functioning properly after installation, retest the unit. See Optional: Insert the Metric Measurement Adapter on page 3.
  - 3. To use bird spikes, insert one spike into each socket around the rim of the cone. The sockets are tapered: push firmly or tap lightly with a hammer for a more secure fit.
  - 4. Place the cone back onto the base by putting the latches on the cone into the latch openings in the base and rotating the cone clockwise until the latches lock into place. As you reattach the cone, make sure to run the cable to the cable slo...
  - 5. Place the debris screen, pointed end up, into the cone. The screen prevents large bits of debris from blocking the funnel hole. If bird nesting is a problem, you can place a spike in the hole on top of the debris screen. Note that using a bird spi...
  - Note: If you choose not to install the bird spikes, we recommend that you keep the packet of spikes in case birds become a problem in the future.
    - 6. To prevent fraying or cutting of the cable where it is exposed to weather, it is important that you secure it so it doesnt whip about in the wind.
Use cable clips or weather resistant cable ties to secure the cable. Place clips or ties approximately every 3 to 5 feet (1 to 1.6 m). Do not use metal staples or a staple gun to secure cables. Metal staples, especially when installed with a staple g...
- Extending Cable Runs
- Adjusting the Rain Collector
  - Note: Modify both adjustment screws by the same amount.
  - Note: Avoid comparison to rainfall readings obtained from television, radio, newspapers, or neighbors readings. Such readings are not an accurate measurement of the weather conditions in your specific location. The rain collector is carefully test...
- Maintaining the Rain Collector
  - 1. Disconnect the rain collector cable from the sensor interface in the transmitter shelter.
  - 2. Separate the cone from the base
  - 3. Use a soft damp cloth to clean pollen, dirt, and other debris from the cone, cone screens, and bucket.
  - 4. Use a pipe cleaner to clear the funnel hole in the cone and the drain screens in the base. When all parts are clean, rinse with clear water.
  - 5. Reattach the cone and replace the debris screen. Reconnect the rain collector cable to the sensor interface.
- Troubleshooting Guide
  - Contacting Davis Technical Support
- Specifications
  - Sensor Type Tipping bucket with magnetic reed switch
  - Output Contact closure
  - Attached Cable 40 (12 m), 4-conductor, 26 AWG
  - Connector Modular connector (RJ-11)
  - Recommended Max.Cable Length 900 (270 m)
  - Housing Material UV-stabilized ABS plastic
  - Dimensions with base, no spikes 9.25 wide x 10.25 high x 11 deep (23.5 x 26 x 28 cm)
  - Collection Area 33.2 in2 (214 cm2)
    - Range
  - Daily Rainfall 0.00 to 99.99 (0.0 mm to 999.8 mm)
  - Total Rainfall 0.00 to 199.99 (0.0 mm to 6553 mm)
    - Accuracy For rain rates up to 2"/hr (50 mm/hr): 4% of total or +0.01 (0.2mm) (0.01" = one tip of the bucket) whichever is greater. For rain rates from 2"/hr (50 mm/hr) to 4"/hr (100 mm/hr): 5% of total or +0.01 (0.2mm), whichever is greater.
    - Update Interval 20 - 24 seconds
  - Input/Output Connections
    - Red Switch terminal
    - Green & Yellow Switch terminal

Davis 7857M Instruction Manual

Pages 12

Year 0

Language(s)

of 12

Davis 7857M Rain Collector Specification

The Davis 7857M Rain Collector is a precision meteorological instrument designed for accurate rainfall measurement. This collector is engineered to work seamlessly with various data logging systems, making it an ideal choice for both amateur weather enthusiasts and professional meteorologists. Constructed from high-quality UV-stabilized ABS plastic, the collector is built to withstand harsh weather conditions, ensuring long-term durability and reliability. The 7857M features a tipping bucket mechanism, which is a time-tested method for capturing rain data with high accuracy. Each tip of the bucket represents a precise measurement, allowing for detailed analysis of rainfall events.

The tipping bucket system is magnetically operated, which reduces friction and wear, thus enhancing the long-term performance of the device. The collector’s design includes a built-in debris screen to prevent clogging, ensuring uninterrupted data collection during heavy rainfall. The funnel-shaped top is optimized for efficient water capture, minimizing evaporation and loss. Installation is straightforward, with options for mounting on a pole or a flat surface, providing flexibility in placement to suit various environmental conditions.

Connectivity is another key aspect of the 7857M, as it is compatible with Davis Instruments’ range of weather stations and data loggers, allowing for seamless data integration and real-time monitoring. The unit is designed with serviceability in mind, featuring easily accessible components for maintenance and calibration. Overall, the Davis 7857M Rain Collector is a robust, reliable, and precise instrument, engineered to provide accurate rainfall data for a wide range of applications.

Davis 7857M Rain Collector F.A.Q.

How do I install the Davis 7857M Rain Collector?

To install the Davis 7857M Rain Collector, securely mount it on a level surface away from obstructions like trees and buildings. Ensure the funnel is clear of debris and the unit is properly aligned.

What maintenance is required for the Davis 7857M Rain Collector?

Regular maintenance involves cleaning the funnel and the tipping bucket mechanism to ensure accurate readings. Check for debris and insects monthly, especially during the rainy season.

How can I troubleshoot inaccurate readings from the rain collector?

First, ensure the collector is level. Then, check for blockages and clean the tipping bucket. Verify that the collector is not subject to vibrations or excessive wind, which can affect accuracy.

How do I calibrate the Davis 7857M Rain Collector?

To calibrate, use a measured amount of water to perform a manual tip test. Adjust the calibration screws to ensure the collector matches the known quantity of water.

What is the best location for installing the rain collector?

The best location is an open area, away from obstructions and at least 4-6 feet above the ground. Avoid placing it under trees or on rooftops where wind can affect readings.

How do I clean the Davis 7857M Rain Collector?

Remove the funnel and use a soft brush and mild detergent to clean it. Gently clean the tipping bucket with water. Avoid using harsh chemicals or abrasive materials.

What should I do if the rain collector stops working?

Check the power source and connections. Ensure there are no physical obstructions. If the issue persists, consult the manual for reset procedures or contact customer support.

Can the Davis 7857M Rain Collector withstand harsh weather conditions?

Yes, it is designed to withstand various weather conditions, including rain, wind, and sun. However, regular maintenance is recommended to ensure longevity and accuracy.

How do I connect the rain collector to a weather station?

Refer to the weather station manual for compatible connections. Typically, you'll need to connect the rain collector's cable to the designated input port on the weather station unit.

What is the typical lifespan of the Davis 7857M Rain Collector?

With proper maintenance, the Davis 7857M Rain Collector can last many years. Regular cleaning and checks will help prevent wear and extend its operational life.