RAINFALL
What if the rain gauge never had to tip?
TruMet PW100 uses infrared optical measurement instead of a tipping mechanism, providing rainfall measurement from 0 to 200 mm/h with 0.1 mm resolution and a pulse output designed to integrate with existing rainfall monitoring systems.
Simulated rainfall, time sped up. Move your pointer up and down to change the intensity.
- Optical rainfall measurement0 to 200 mm/h with 0.1 mm resolution
- Nothing to tip or blockInfrared measurement replaces the tipping mechanism
- Sealed to IP66For sites where regular inspection is not practical
- Pulse outputOne pulse per 0.1 mm, for existing rainfall systems
The measurement
Rain doesn't wait for someone to check the gauge
Rainfall measurement often happens in places where regular inspection is inconvenient, expensive or simply not practical.
Traditional tipping-bucket gauges rely on a mechanical mechanism to collect and tip accumulated rainfall. If that mechanism becomes blocked, the measurement can be affected without anyone knowing until the gauge is checked.
TruMet PW100 takes a different approach. Infrared optical measurement detects rainfall without a tipping mechanism, removing the mechanical movement from the measurement itself. Where rainfall belongs alongside the rest of the weather, six MaxiMet models measure it in the same instrument.
Nothing to tip
Infrared optical measurement replaces the tipping mechanism.
Pulse output
One pulse per 0.1 mm, the same as one tip of a bucket.
Sealed to IP66
For sites where regular inspection is not practical.
Or in the station
MaxiMet models with optical rainfall in the same instrument.
The range
One rain gauge, or rainfall in the station
TruMet PW100 measures rainfall from 0 to 200 mm/h, with 0.1 mm resolution and IP66 protection. Its pulse output provides one pulse per 0.1 mm, so it can interface with systems designed to accept a conventional tipping-bucket rainfall input. Six MaxiMet weather stations measure rainfall alongside the rest of the weather.
TruMet PW100
The rain gauge on its own. Infrared optical rainfall with a tipping-bucket pulse output, so it replaces a tipping bucket on the same input.
MaxiMet GMX240
Wind and optical rainfall, for sites where temperature, humidity and pressure are measured elsewhere.
MaxiMet GMX400
Temperature, humidity, pressure and optical rainfall, for sites with no need for wind.
MaxiMet GMX550
Wind, T/H/P and rainfall, optical or tipping bucket. One of the two MaxiMet models with a tipping-bucket input that TruMet can drive.
MaxiMet GMX551
The GMX550 measurement set plus solar radiation, with the same tipping-bucket input for a TruMet.
MaxiMet GMX600
Wind, temperature, humidity, pressure and standard optical rainfall, 0 to 300 mm/hr, in one instrument.
MaxiMet GMX603
The most accurate rainfall in a compact station. TruMet rainfall built in, 0 to 200 mm/hr at 5% or better, with wind and T/H/P.
No single Rainfall does all of that. Our team can suggest a pairing.
Choosing between them
A gauge on its own, or rainfall in the station
TruMet PW100 replaces a tipping bucket on the same input. A MaxiMet with rainfall measures it alongside the rest of the weather. The GMX603 carries TruMet rainfall built in, and the GMX550 and GMX551 are the only MaxiMet models with a tipping-bucket input a TruMet can drive.
| Specification | Standalone gaugeTruMet PW100 | TruMet built inGMX603 | Standard opticalGMX600 | Pairs with TruMetGMX550 |
|---|---|---|---|---|
| Choose it when | You want to keep the existing logger and change the gauge | Rainfall accuracy matters most, alongside wind and T/H/P | You need rainfall with wind and T/H/P in one instrument | You want a full station with a TruMet on its tipping-bucket input |
| Rainfall | Optical, 0 to 200 mm/hr | Optical, 0 to 200 mm/hr | Optical, 0 to 300 mm/hr | Optical or tipping bucket |
| Accuracy | 5% | 5% or better | See datasheet | See datasheet |
| Also measures | No | Wind, T/H/P | Wind, T/H/P | Wind, T/H/P |
| Takes a TruMet | No | Built in | No | Tipping-bucket input |
| Ingress protection | IP66 | IP66 | IP66 | IP66 |
| Weight | 0.67 kg | 1.1 kg | 0.8 kg | 0.7 kg |
| Datasheet | Datasheet | Datasheet | Datasheet | Datasheet |
The technology
Take the tipping out of the rain gauge
TruMet PW100 uses infrared optical measurement to detect precipitation rather than relying on a mechanical tipping bucket. That means there is no bucket to tip, no mechanism to empty and no moving sensing element to stick.
The result is a solid-state approach to rainfall measurement for monitoring systems where unattended operation and straightforward integration matter.
Integration
Change the measurement, not the whole system
Replacing a tipping-bucket gauge does not necessarily mean replacing the logger or monitoring system that receives its output. TruMet PW100 provides one pulse per 0.1 mm, allowing it to interface with systems using a tipping-bucket-style rainfall input.
That makes the integration question straightforward: establish what the existing station or logger expects, then confirm the pairing before specification.
Optical versus tipping bucket
How the two approaches differ, and where removing the mechanism matters most.
Read the comparison →Check the logger input
TruMet gives one pulse per 0.1 mm. Confirm the existing station or logger accepts a tipping-bucket input.
See technical information →Rainfall in the station
Six MaxiMet models measure rainfall in the same instrument as the rest of the weather.
Explore MaxiMet →Applications
Rainfall measurement where the visit costs more than the gauge
Remote monitoring stations, environmental networks and unattended installations can make routine inspection difficult. In those applications, removing a mechanical tipping mechanism can simplify the measurement architecture and reduce one source of mechanical failure from the installation.
HydrometeorologyRainfall intensity from 0 to 200 mm per hour, with a pulse output that matches the tipping-bucket record a network already holds.Catchment and hydrometeorology →
Flood monitoringFlood warning depends on gauges that keep reporting during the heaviest rain, with no tipping mechanism to block.Flood warning and water level →
AgricultureRainfall figures for scheduling and record keeping, from a TruMet or a MaxiMet with rainfall.Agriculture →
Water managementCatchment, reservoir and drainage teams already run tipping-bucket inputs. TruMet delivers one pulse per 0.1 mm into that same input.Drainage, SUDS and attenuation →
Solar sitesSolar farms put gauges where nobody wants to go. Less susceptibility to debris blockage means longer runs between visits.Solar site monitoring →
Environmental monitoringLong-running environmental sites need instruments that survive unattended. TruMet is IP66 and operates from -35 to +70 °C.Research and environment →Technical information
The rainfall record starts with the measurement
| Specification | TruMet PW100 | GMX603 | GMX600 | GMX240 | GMX400 | GMX550 | GMX551 |
|---|---|---|---|---|---|---|---|
| Rainfall | Optical, infrared | Optical, TruMet built in | Optical | Optical | Optical | Optical or tipping bucket | Optical or tipping bucket |
| Intensity range | 0 to 200 mm/hr | 0 to 200 mm/hr | 0 to 300 mm/hr | 0 to 300 mm/hr | 0 to 300 mm/hr | See datasheet | See datasheet |
| Accuracy | 5% | 5% or better | See datasheet | See datasheet | See datasheet | See datasheet | See datasheet |
| Also measures | Rainfall only | Wind, T/H/P | Wind, T/H/P | Wind | T/H/P | Wind, T/H/P | Wind, T/H/P, solar |
| Takes a TruMet | Is the TruMet | Built in | Not supported | Not supported | Not supported | Pairs, tipping-bucket input | Pairs, tipping-bucket input |
| Ingress protection | IP66 | IP66 | IP66 | IP66 | IP66 | IP66 | IP66 |
| Weight | 0.67 kg | 1.1 kg | 0.8 kg | 0.5 kg | 0.5 kg | 0.7 kg | 0.8 kg |
When specifying a rainfall sensor, consider the rainfall intensity range, resolution, output format, compatibility with the existing logger or station, environmental protection, installation, power and the required data collection interval. TruMet PW100 measures liquid precipitation only, with a measurement temperature range of 0 °C to +70 °C, so it does not measure snow or hail. The GMX550 and GMX551 also accept a tipping-bucket gauge.
Technical resources
Datasheets and manuals for Gill rainfall measurement
Questions
Frequently asked questions
What is an optical rain gauge?
An optical rain gauge measures rainfall using optical sensing rather than a mechanical tipping mechanism. Gill’s TruMet PW100 uses infrared optical measurement to detect precipitation.
How does an optical rain gauge work?
An optical rain gauge uses infrared optical sensing to detect precipitation as it passes through the measurement area. TruMet PW100 uses this approach instead of a tipping bucket.
What is the difference between an optical rain gauge and a tipping-bucket rain gauge?
A tipping-bucket rain gauge uses a mechanical mechanism to collect and tip measured quantities of rainfall. An optical rain gauge such as TruMet PW100 uses infrared optical measurement instead, with no tipping mechanism.
Why use an optical rain gauge?
An optical rain gauge removes the mechanical tipping mechanism from the rainfall measurement. This can be useful in remote or unattended installations where mechanical blockage or movement could affect measurement.
What rainfall rate can TruMet PW100 measure?
TruMet PW100 measures rainfall from 0 to 200 mm per hour.
What output does TruMet PW100 provide?
TruMet PW100 provides one pulse per 0.1 mm of rainfall, allowing it to interface with systems designed to accept a tipping-bucket-style pulse input.
Can TruMet PW100 replace a tipping-bucket rain gauge?
It can be used as a replacement where the existing station or logger can accept the TruMet PW100 pulse output. The existing system specification should be confirmed before replacement.
Is TruMet PW100 suitable for remote monitoring?
Its optical, non-mechanical measurement approach makes TruMet PW100 suitable for rainfall monitoring applications where avoiding a tipping mechanism is beneficial. The complete installation should be assessed against the environmental and system requirements.
Where can I find the TruMet PW100 datasheet?
The TruMet PW100 product page and Gill resources library provide the available product documentation and technical specification.
Have an application to discuss?
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Tell us what you need to measure, where and under what conditions. We'll help you work out the appropriate approach.
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