Ultrasonic
AM-ULM-B Small Blind Area Ultrasonic Level Meter
Short-span ultrasonic level meter for shallow wells and tanks: 0–3 m, blind zone under 0.1 m, ±0.15 % and 1 mm resolution, 4–20 mA or Modbus.
- Model
- AM-ULM-B
- Category
- Ultrasonic
- Outputs
- 4–20 mA, RS485, Modbus RTU
- Lead time
- 7–10 working days for standard
- MOQ
-
1 pc
10 pcs for OEM - OEM available
- Yes
An ultrasonic level meter times a pulse from a transducer above the liquid down to the surface and back. AM-ULM-B is the short-span version: 0–3 m, a blind zone under 0.1 m, 1 mm of display resolution and ±0.15 % in the parameter table. It is for the vessel where the useful band sits low — a collecting well, a dosing tank, a sump — and the top of the tank is close enough that a metre of dead space would swallow the alarm point.
Three metres is the whole span, so a taller tank is a different instrument rather than a setting. The datasheet also fixes the rest of the envelope: atmospheric pressure only, ambient −20 to +60 °C, IP65, a G2 process connection and an M20×1.5 cable entry. What the buyer gives up is the medium side — no wetted material, no medium temperature and no chemical-resistance data are published, so acid, alkali or high-temperature service cannot be signed off from the sheet, and foam or a churning surface leaves nothing to time.
Technical specifications
| Measuring principle | Ultrasonic, non-contact: a transducer above the liquid sends a pulse and times the echo from the surface; nothing enters the medium |
|---|---|
| Range | 0–3 m |
| Blind zone | < 0.1 m |
| Accuracy | ±0.15 % |
| Display resolution | 1 mm |
| Frequency | 20–350 kHz |
| Wiring | Two-wire (AM-ULM-B-2W) or four-wire (AM-ULM-B-4W) |
| Supply | 24 V DC (two-wire); 24 V DC or 90–240 V AC (four-wire) |
| Power consumption | < 3 W |
| Output | 4–20 mA into 250 Ω (two-wire); 4–20 mA into 510 Ω (four-wire) |
| Communication | RS485 Modbus (four-wire) |
| Relay | 250 V AC / 5 A or 30 V DC / 2 A (four-wire) |
| Display | LCD |
| Ambient temperature | −20 to +60 °C |
| Pressure | Atmospheric pressure |
| Process connection | G2 |
| Electrical connection | M20×1.5 |
| Protection | IP65 |
Every value above is on the datasheet: AM-ULM-B Small Blind Area Ultrasonic Level Meter Datasheet (PDF · 128.1 KB)
What it is not the answer for
Read this before asking for a price: one of these conditions is what turns a good meter into a bad installation.
- A vessel deeper than 3 m: the range ends there, and a longer span is another instrument, not a setting
- Foam, heavy steam or a churning surface: the echo is scattered or never returns, and a meter that times echoes has nothing to time
- A closed vessel under pressure: the parameter table gives atmospheric pressure only
- An alarm point inside the top 0.1 m: the blind zone is exactly where a high-level trip usually sits
- Acid, alkali or high-temperature service: the datasheet publishes no wetted material, no medium temperature and no chemical-resistance data to check it against
- A hazardous area: no explosion-proof version or approval appears in the datasheet
Where the surface foams, the vapour is heavy or the span runs past 3 m, the neighbouring principle is the answer: a radar that times the surface without an acoustic echo to lose, or a submersible transmitter that reads the head of water at the bottom of the well.
Maintenance and service life
Nothing in the wetted path moves, so the service is the transducer face. Wipe it when the medium leaves a film — grease, scale or dried slurry lengthens the dead zone until it swallows the echo. Check the reading against a hand measurement after cleaning and after any change of medium or process temperature, and inspect the M20×1.5 gland at the same visit: IP65 ends at a perished seal.
Behind the instrument
How it is built and tested
Coil winding, the calibration bench, the plant floor — and an overseas customer's factory audit.
What buyers ask before ordering
- What does the small blind zone buy me?
- 0.1 m of dead space at the top instead of the half metre or metre a general-purpose ultrasonic leaves, and the display resolves 1 mm. On a 3 m collecting well that is the difference between seeing the last 100 mm before the dry-run level and losing it to the blind zone.
- Should I take two-wire or four-wire?
- The two-wire AM-ULM-B-2W runs on 24 V DC and gives 4–20 mA into 250 Ω. The four-wire AM-ULM-B-4W takes 24 V DC or 90–240 V AC, gives 4–20 mA into 510 Ω, and adds RS485 Modbus and a relay rated 250 V AC / 5 A or 30 V DC / 2 A.
- Can it go in a tank under pressure?
- No. The parameter table lists atmospheric pressure, so a closed vessel under pressure is outside the instrument. If the tank is sealed and pressurised, we would need the working pressure and the vapour above the liquid, and the answer would be a radar or a pressure transmitter rather than this meter.
- How good is the ±0.15 %?
- It is what the parameter table prints, and the display resolves 1 mm. The datasheet does not say whether the percentage is taken on the span or on the reading, so a 3 m vessel is set from the 1 mm resolution and the percentage as printed; we would need your alarm points and the repeatability you want to say more.
- Which materials touch the medium?
- The datasheet gives a G2 process connection, an M20×1.5 electrical entry and IP65, but no wetted material, no medium temperature and no chemical-resistance data. The introduction mentions acid, alkali and high temperature without tying them to a material, so we would need the medium, its concentration and its temperature to answer.
- What do you need from me to quote?
- The depth of the vessel and the band you actually use, whether the top 100 mm carries an alarm, the medium and whether it foams, the supply you have — 24 V DC or 90–240 V AC — and whether the control system wants 4–20 mA, Modbus or a relay contact.
Still not sure which version fits your line? Send the medium and the process conditions — we answer with the configuration, not a catalogue.
Applications
Where this model is used
Each application names a measuring point and the conditions that decide the selection.
WW-PS
Pump Station Wet Well Level and Pressure
Wet well level control and rising main pressure for sewage pump stations, where foam and grease blind a non-contact sensor.
WW-IP
Industrial Process Measurement
Flow, level and water quality in chemical, food and pharmaceutical processes, where wetted materials and signal compatibility decide the choice.
Elsewhere in the range
Other models in Ultrasonic
The same category holds the models that solve the neighbouring problem, and the price difference is usually smaller than the cost of the wrong principle.
AM-ULM
AM-ULM Ultrasonic Level Meter
Non-contact ultrasonic level meter for open tanks, sumps and channels, with a small blind zone and a Modbus output.
AM-ULM-D
AM-ULM-D Ultrasonic Level Differential Meter
Two-probe ultrasonic differential level meter: 0–25 m difference range, ±0.5 %, two relays, 90–240 V AC or 12–24 V DC, 4–20 mA and Modbus.
AM-ULM-EX
AM-ULM-EX Explosion-proof Ultrasonic Level Meter
Explosion-proof ultrasonic level meter for hazardous areas: Ex db ia IIC T6 Gb, 0–30 m, ±0.5 %, 1 mm resolution, 4–20 mA and RS485.
Measuring point does not match the table above?
Send the medium, the pipe size and the output your control system expects. We answer with the principle that fits, or with the reason none of ours does.