Company Profile

FH950 Velocity Flow Meter: Hach Portable Open Channel Stream Probes

Quick Answer: The Hach FH950 is a portable velocity meter for open channel stream measurements. If you need a similar probe with local support in Southeast Asia or a lower price, Silver Automation Instruments offers alternative portable electromagnetic and ultrasonic flow meters for field use.

In practice, many water engineers in Vietnam, the Philippines, and Bangladesh use the Hach FH950 for river gauging and wastewater discharge monitoring. The meter measures flow velocity with an electromagnetic sensor that has no moving parts. It logs velocity and depth data to a handheld display in real time.

Here is the thing. When a customer asked us last year for a replacement for an FH950 that had a cracked probe body after two years in a sandy canal, we looked at the failure mode. The Hach sensor used a plastic housing that could not handle constant abrasion from suspended silt. We supplied a portable meter with a 316L stainless steel sensor body. The new probe has been working without issues for 11 months now.

The FH950 covers a velocity range of 0 to 6 m/s. Accuracy is ±2% of reading plus ±0.015 m/s, based on the manual of the device. It includes a pressure transducer for depth measurement up to 10 meters. The probe is rated IP68, so it can stay submerged for short periods. It is commonly used in clean river water with conductivity above 100 µS/cm.

Because the FH950 relies on the Faraday electromagnetic principle, it needs a minimum liquid conductivity. In low-conductivity streams, such as rain runoff with less than 50 µS/cm, readings can drift. In these cases, some engineers switch to an ultrasonic Doppler velocity meter that does not require conductivity at all.

Silver Automation Instruments manufactures a portable open channel flow meter with a Doppler ultrasonic sensor. The velocity range is 0.02 m/s to 5 m/s. It works in water with suspended solids or bubbles, even at 0 µS/cm. The meter includes a depth sensor and a data logger with USB export. We have shipped these units to a paint manufacturer in Thailand and a mining company in Ghana.

For applications that match the electromagnetic method of the FH950, Silver offers the SVD-100 portable velocity meter. It uses an electromagnetic probe with a velocity range of 0.01 m/s to 5 m/s, accuracy ±2% of reading, and operates in liquids from 20 µS/cm. The probe material is 316L stainless steel, and the handle is reinforced fiberglass. It includes a pressure depth sensor with 0.5% full scale accuracy. The whole kit fits in a hard case and weighs 4.8 kg. That is lighter than the Hach FH950 case, which some field teams in Indonesia told us is important when they walk 2 km to a monitoring point.

Most engineers skip this part, but we always remind: check the cable length and connector type. The Hach FH950 uses a proprietary connector. If the cable gets damaged in the field, you may wait weeks for a replacement. Our portable flow meters use a standard military-style connector with a detachable cable. Spare cables are available from our stock in Nanjing and can be sent to Kuala Lumpur or Dubai within 3 working days.

When you need to buy a portable velocity flow meter for open channel stream probes, send us your maximum flow velocity, channel width, water conductivity, and required cable length. We will propose a suitable meter with a price quote the same day.

Contact Silver Automation Instruments:
Email: [email protected]
Tel: +86-25-68650347
Whatsapp: +86-25-52155837
WeChat: +86 15365082610
See our portable flow meters at https://flow-meter.com.au.

FAQ

What is the measuring principle of the Hach FH950? It uses electromagnetic induction based on the Faraday law. The probe generates a magnetic field. As water flows past the electrodes, it produces a voltage proportiona