Level Measurement · Ultrasonic Level Meters
Non-contact ultrasonic level meter for tanks, sumps, channels and silos, in integral and separate forms, with 4-20 mA and RS-485 outputs and a relay pair.
SIN-MP-C (4 models) ·
An ultrasonic level meter is bought for what it does not touch. Where a vessel holds sewage, an acid, a food product or a slurry, a wetted instrument has to survive the medium and be cleaned afterwards, and a float or a probe has to be got at. Measuring from above the surface avoids all of it: the transducer sits in the air over the vessel and the contents never reach it.
What that buys in simplicity is paid for in geometry. The instrument needs a clear path from its face to the surface, and on a vessel with anything in it that is a smaller concession than it first appears.
The transducer sends a burst of sound downwards and then listens. The pulse reflects from the change in density at the surface and returns, and the interval between transmission and reception gives the distance; subtracting that from the mounting height gives the level. Because the speed of sound depends on the temperature of the air it travels through, the instrument carries a temperature sensor and corrects the timing for it, which is why the temperature of the installation is part of the selection rather than an ambient detail.
Three geometric limits follow from that single sentence, and between them they decide whether a vessel can be measured at all. Directly beneath the face there is a band where the instrument cannot separate its own transmission from the returning echo, and the highest level the vessel may reach has to stay below it. The pulse spreads as it travels, so on a tall narrow vessel the beam can reach the wall or an internal fitting and return a false echo before the surface does. And for a given range there is a minimum distance between the transducer and the vessel wall, because the wall reflection arrives close in time to the surface reflection.
The two forms differ only in where the head is. The integral form carries the transducer in the head and is mounted on the vessel, which is the arrangement for a tank with clear space above it and a top that can be reached. The separate form puts the transducer on the vessel and the head wherever a person can read it, which is what a low headroom space, a vessel with no access at the top or a washdown zone requires.
There are two consequences beyond convenience. The separate form takes a mains supply as well as a low-voltage one, so it suits a plant where a supply is available at the vessel but no low-voltage feed is. And it does not carry the wireless option that the integral form offers, so a remote site with no wiring at all points to the integral form instead.
Range and accuracy are the figures a buyer looks for first, and on this type they are not enough on their own. The blanking distance belongs to the transducer arrangement rather than to the range, which is why the material gives different figures for the integral and the separate forms across the same spans, and why a form with a short blanking distance can be the one that makes a shallow vessel measurable. The small-blanking form exists for exactly that case: it covers a vessel no deeper than a metre or two, with a blanking distance measured in centimetres rather than in tens of centimetres.
That relationship is the reason the specification conversation starts with the vessel rather than with the instrument. The height of the vessel and the highest level the contents reach together decide whether the instrument can be mounted high enough to keep that level out of the blanking band, or whether the range, the mounting or the technology has to change.
The instrument provides a 4-20 mA analogue output and an RS-485 connection speaking Modbus-RTU, which is the standard route into a controller or a control system, and a pair of relay contacts rated for mains switching. The relays are what let one instrument do a job rather than only report one: a level switch that starts a pump or opens a valve needs a contact, and an alarm needs another. The separate form offers four contacts as an option where more actions are needed.
An analogue output accuracy of 0.2 % of full scale is given separately from the measuring accuracy, and the two are worth keeping apart: the first describes the quality of the signal between the instrument and whatever reads it, and the second describes the measurement itself.
The limitations of the technology are the three geometric ones above, and they are worth stating plainly because each has a workaround that is cheaper than changing instrument. A level that reaches into the blanking band can sometimes be dealt with by raising the mounting or by bringing a standpipe up above the vessel. A beam that reaches the wall can be narrowed, or the instrument moved, or the vessel measured by a different principle. But where the air above the surface carries vapour, condensation, dust or foam, geometry does not help, and radar is usually the answer - which is why the boundary between the two technologies is drawn by the atmosphere above the medium rather than by the level range, since both cover the same spans.
The material also leaves several figures unsettled, and they are listed rather than glossed. The accuracy is expressed three different ways across the same document, and an accuracy class is not the same quantity as a percentage of full scale. The blanking distance differs between the two forms for one range. The supply arrangement differs between them. And the relationship between the optional wireless module and the separate 4G unit is not explained.
The items that fix the answer are the vessel height, its diameter and the highest and lowest levels in service; the medium and the vapour or dust above it; the working and extreme temperatures at the instrument; whether foam, condensation or turbulence forms on the surface; what is inside the vessel and how close the instrument can be mounted to the wall; whether the reading has to be seen locally or only as a signal; the outputs required and what will read them; whether any wiring exists at the vessel; and the power available. A vessel drawing answers most of these at once, and it is the single most useful item in the enquiry. Quantity, destination port and required delivery date complete it.
Every value below is taken from source documentation. Where a parameter is not stated in the available material it is marked as information required rather than estimated.
| Range | 0 to 5 m, 0 to 10 m and 0 to 15 m on the integral and separate forms; 0 to 1 m and 0 to 2 m on the small-blanking form; 0 to 5 m on the basic formStandard |
|---|---|
| Accuracy | ±0.3 % of full scale on the main forms and 0.5 % on the small-blanking form; the material also describes the upgraded units as 0.3 class and refers elsewhere to a 0.5 % and 0.3 % pair, and an accuracy class and a percentage of full scale are not the same quantityInformation required |
| Resolution | 1 mmStandard |
| Analogue output accuracy | 0.2 % of full scaleStandard |
| Blanking distance, integral form | ≤0.4 m at the 5 m and 10 m ranges and ≤0.6 m at the 15 m rangeStandard |
| Blanking distance, separate form | ≤0.3 m, ≤0.35 m and ≤0.5 m at the 5 m, 10 m and 15 m rangesStandard |
| Blanking distance, small-blanking form | ≤6 cm at the 0 to 1 m range and ≤10 cm at the 0 to 2 m rangeStandard |
| Basic form display | Level, distance and temperature togetherStandard |
| Supply | Integral form 18 to 28 V DC; separate form 100 to 240 V AC at 50/60 Hz or 18 to 28 V DCStandard |
|---|---|
| Analogue output | 4-20 mA, isolated on the separate form, with a maximum load of 500 ΩStandard |
| Communication | RS-485 with Modbus-RTU; a four-wire option on the integral formStandard |
| Relay outputs | Two SPST contacts rated 250 V AC at 3 A; a four-relay option is offered on the separate formStandard |
| Wireless | Optional NB-IoT or 4G on the integral form; not offered on the separate formOptional |
| Temperature compensation | AutomaticStandard |
| Menu language | Chinese and EnglishStandard |
| Ingress protection | Instrument IP65, probe IP68Standard |
|---|---|
| Working temperature | Instrument -20 to 60 °C, probe -20 to 80 °CStandard |
| Electrical connection | M20 × 1.5 or M16 × 1.5 on the integral form; M20 × 1.5 on the separate formStandard |
| Integral form dimensions | Top diameter 102 mm, controller section 121 mm high, probe section 103.5 mm high with a 56 mm diameterStandard |
| Separate form dimensions | Head 200 × 150 mm with mounting holes at 170 × 130 mm centresStandard |
| Separate form probes | A G2 threaded probe for the 5 m and 10 m ranges, and an M78 × 2 threaded probe for the 15 m rangeStandard |
| Weight | Not stated in the materialInformation required |
| Maximum pressure at the probe | Not stated in the materialInformation required |
| Flat-roofed tank | Flange mounting, with the relationship between the highest liquid level and the blanking distance checked firstStandard |
|---|---|
| Arched-roof tank | Nozzle mounting with the nozzle under 70 mm, referenced to the transducer faceStandard |
| Bracket and open tank | A bracket with a six-bolt platform, or direct mounting on an open vessel, with the transducer face square to the surfaceStandard |
| Drainage well | A standpipe with an internal diameter of at least 150 mm, taking account of the blanking distance and the rangeStandard |
| Solids silo | The transducer face square to the surface of the material, with the blanking distance and the range checked as for a liquidStandard |
| Minimum distance from the wall | Given in the material per range, from 0.5 m at a 5 m range to 7 m at a 70 m range, and increased further where false echoes appearStandard |
| Scope | Additional forms supplied in November 2026 for this product type. Figures below are from that batch; where they differ from the rows above, both are recorded rather than merged.Standard |
|---|---|
| Range | 0 to 5 m and 0 to 20 mStandard |
| Accuracy | 0.5 class, quoted as plus or minus 0.5 %Standard |
| Output | 4-20 mA, RS-485 and relay contactsStandard |
| Supply | 24 V DC, 220 V AC and battery-powered versionsStandard |
| Process connection | Threaded and flangedStandard |
| Ingress protection | IP65, with IP68 versionsStandard |
| Model | Configuration | Key ranges | Availability |
|---|---|---|---|
| SIN-MP-C | Integral form with the transducer in the head, described for stirred tanks and general duties | 0 to 5 m, 0 to 10 m and 0 to 15 m; ±0.3 % of full scale; 18 to 28 V DC; optional NB-IoT or 4G | The form for a vessel with clear space above it |
| SIN-ULS-B | Separate form with the head and the probe mounted apart | 5 m, 10 m and 15 m ranges; ±0.3 % of full scale; 100 to 240 V AC or 18 to 28 V DC; no wireless option | The form for a confined space above the vessel or a vessel top that cannot be reached |
| SIN-WSU100 | Small-blanking form for small vessels and confined spaces | 0 to 1 m at a blanking distance of ≤6 cm and 0 to 2 m at ≤10 cm; 0.5 % accuracy | |
| WSU200 | Basic form with a display showing level, distance and temperature together | 0 to 5 m |
Certifications are only published once a certificate copy can be produced, so this section is deliberately empty rather than populated with assumed approvals. Tell us which approvals your application requires and we will confirm what is available for this instrument.
The following are required for a complete specification but are not stated in the documentation supplied to us. They are listed rather than estimated:
The vessel, not the level range. Four things come first: the vessel height and the highest level the contents reach, because the second of those has to stay clear of the blanking distance; the vessel diameter and anything protruding into it, because the beam spreads as it travels and reads whatever comes back first; where the instrument can be mounted and whether that point can be reached for reading; and the atmosphere above the medium, since vapour, condensation, dust and foam each affect the returning echo differently from clean air. A vessel drawing answers all four, and it is more useful than a range figure.
Because the integral and the separate forms use different transducer arrangements, and the blanking distance belongs to the transducer rather than to the range. The material gives ≤0.4 m at the 5 m and 10 m ranges on the integral form and ≤0.3 m at the 5 m range on the separate form, which is a meaningful difference on a shallow vessel. It matters because the highest level the vessel is allowed to reach has to sit below that band, so the form with the shorter blanking distance can be the one that makes a vessel measurable.
That has to be settled rather than read off, and the material is the reason: its specification table gives ±0.3 % of full scale, its model descriptions use an accuracy class, and a general statement elsewhere refers to a 0.5 % and 0.3 % pair. An accuracy class and a percentage of full scale are not the same quantity and should not be converted into one another, so the figure that applies to a given order is listed as information required rather than resolved here. The small-blanking form is given separately at 0.5 %.
When the head cannot be read where the transducer has to be. The separate form puts the transducer on the vessel and the head where a person can reach it, which is the arrangement for a low or confined space above a tank, a vessel top with no access, or an installation where the head would otherwise sit in the sun or in a washdown zone. The separate form also takes a mains supply alongside the low-voltage option, which the integral form does not, and it does not carry the wireless option. Those three differences usually decide the choice between them.
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