TB4MM-L Metric Rain Gage with 8 in. Orifice

Overview

The TB4MM, manufactured by HS Hyquest Solutions, is a high-end tipping bucket rain gage that monitors rainfall in metric rather than US units. It has a 20.3 cm orifice and measures rainfall in 0.2 mm increments. The TB4MM is ideal for locations where intense rainfall events may occur. This tipping bucket is compatible with all Campbell Scientific data loggers, and it is used in environmental monitoring applications.

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Benefits and Features

  • More accurate measurement of high-intensity precipitation
  • High precision—tips at 0.2-mm increments
  • Compatible with most Campbell Scientific data loggers
  • Compatible with the CWS900-series interfaces, allowing it to be used in a wireless sensor network

The "-L" on a product model indicates that the cable length is specified at the time of order.

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Detailed Description

The TB4MM funnels precipitation into a bucket mechanism that tips when filled to its calibrated level. Each tip is marked by a dual reed switch closure that is recorded by a data logger pulse count channel. After measurement, the water drains through two orifices (accepts 12 mm tubing) in the base, allowing the measured water to be collected in a separate container.

The TB4MM contains an internal siphon mechanism that causes rain to flow at a steady rate to the tipping bucket mechanism (regardless of intensity). The siphon allows the sensor to make accurate measurements over a range of 0 to 50 cm per hour.

 

Specifications

Sensor Type Tipping bucket with siphon and dual reed switch
Rainfall per Tip 0.2 mm (0.008 in.)
Measurement Range 0 to 700 mm/h (0 to 27.6 in./h)
Measurement Uncertainty
  • ±2% @ < 250 mm/h (9.8 in./h)
  • ±3% @ 250 to 500 mm/h (9.8 to 19.7 in./h)
Measurement Uncertainty 700 mm/h (27.6 in./h) maximum rate per hour
Operating Temperature Range 0° to 70°C
Humidity Range 0 to 100%
Cable Type Two-conductor shielded
Drain Tube Size Both filters accept 12 mm (0.47 in.) ID tubing.
Orifice Diameter 20 cm (7.9 in.)
Height 33 cm (13 in.)
Weight 2 kg (4.4 lb) with 7.62 m (25 ft) signal cable

Compatibility

Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Data Loggers

Product Compatible Note
CR1000 (retired)
CR1000X (retired)
CR3000 (retired)
CR310
CR350
CR6
CR800 (retired)
CR850 (retired)

Additional Compatibility Information

Mounting

The base of the gage is supported by three legs. A CM240 Leveling Base and Mount or a user-supplied baseplate with leveling capability is recommended. The CM240 may be attached to a CM300-series mounting pole, or to a user-supplied 1.5 IPS (1.9-inch outer diameter, unthreaded) pipe (see Ordering Information). A concrete pad is recommended.

Wind Screen

Campbell Scientific offers the 260-953 Wind Screen to help minimize the affect of wind on the rain measurements. This wind screen consists of 32 leaves that hang freely and swing as the wind moves past them.

Frequently Asked Questions

Number of FAQs related to TB4MM-L: 9

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  1. If a data logger is not registering any tips from a rain gage, what can be done?

    The following are some suggestions to try:

    1. Check that there is a solid connection to the reed switch. The screws should be tight, and the wires should have a solid connection to the screws.
    2. Try switching the connection from the current reed switch being used to the secondary reed switch connection.
    3. Check that the cable is connected to the correct input on the data logger. Take the two wires on the other end of the cable (the sensor side) and touch them together. The data logger should register a tip. If the tip registers, the issue is with the reed switch. Replace the reed switch.
    4. If the data logger still doesn't register a tip, try using a different cable.

  2. What are the indicators that a tipping bucket rain gage has a faulty reed switch?

    Not registering any tips, missing tips, or double tips.

  3. What can cause a data logger to not receive correct tipping data from a rain gage?

    If data is not being logged correctly, there are two likely causes:

    • The reed switch has failed.
    • There is a faulty connection from the rain gage to the data logger, typically caused by a broken conductor or corroded wiring. 
  4. What are the steps to perform a field calibration check on a TB4-L, a TB4MM-L, or a CS700-L?
    1. Remove the housing assembly from the base by removing the three screws and lifting upward on the housing.
    2. Check the bubble level to verify the rain gage is level.
    3. Pour water through the inner funnel to wet the two bucket surfaces. Using a graduated cylinder, slowly pour 314 cc (19.16 in3) of water, over a 15 minute period, into the collection funnel. This volume of water is equal to 0.39 inches of rainfall (10 mm).
    4. After the water has passed through the rain gage, the tipping bucket should have tipped 39 times for the TB4-L or CS700-L, or 50 times for the TB4MM-L.
    5. If the rain gage fails to record the correct number of tips, return the unit to Campbell Scientific for recalibration.
  5. What type of wind screen can be used for a tipping bucket rain gage?

    The 260-953 Alter-type rain gage wind screen consists of 32 heavy metal leaves that hang freely and swing as the wind moves past them. The swinging leaves act as a wind damper and help minimize the effect of wind on the rain measurements without adding additional turbulence.

  6. What are the indicators that a tipping bucket rain gage is out of calibration?

    Not enough tips or too many tips.

  7. What can cause a tipping bucket rain gage to be out of calibration?

    When a rain gage is out of calibration, it is usually because of the buildup of dirt and grime on the internal surfaces of the tipping bucket mechanism. Cleaning the internal surfaces usually brings the rain gage back into calibration. It is also possible that a rain gage is out of calibration because it is no longer level.

    To minimize the possible occurrence of calibration errors, perform routine cleaning and maintenance of the rain gage at least once every three months. The environmental conditions at a particular site may require a facility to perform cleaning, leveling, and maintenance on a much more frequent schedule.

  8. What are the most common errors with a tipping bucket rain gage?

    The most common errors are either that the rain gage appears to have drifted out of calibration or that the tips are not being correctly recorded by the data logger. 

  9. What is needed to connect a sensor that is compatible with wireless sensor interfaces to a CR800, CR1000, or CR3000 in a wireless network?

    To incorporate a sensor that is compatible with wireless sensor interfaces into a wireless network, a CWS900-series wireless sensor interface is needed, as well as an A205 CWS-to-PC interface to configure it. 

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