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The FS‑SMSB‑ST‑100 is a rugged solid‑state point level switch sensor optimized for industrial liquid detection. The “SMSB” portion places it within the miniature switch family of the FS sensor line, while “ST” suggests a specialty treatment or structural type (for example, “stem type” or “standard extension”). The numeric “100” indicates the version or model number within that product variant.
This sensor is designed to provide dependable on/off detection of fluids or interfaces at a specific threshold. It delivers a discrete signal rather than a continuous analog measurement. Built for harsh environments, FS‑SMSB‑ST‑100 features chemical resistance, compact size, and reliable switching behavior.
It is typically used in control loops, alarm systems, safety cutoffs, and automation schemes where detecting “liquid present / liquid absent” is critical. The ST version may offer enhanced mechanical durability or extended stem length compared to base models.
High or low level detection in tanks, sumps, or vessels
Overflow alarm triggering
Dry-run protection for pumps
Interface detection in liquid layering systems
Industrial automation systems for binary fluid presence detection
Wastewater, chemical, or utility fluid systems
Discrete on/off output — simplifies system logic and reduces analog signal handling
Compact and robust — well suited to tight spaces and mechanical stress
Chemical resistance — built from materials compatible with many process fluids
Fast switching — prompt detection ensures timely control response
Mechanical flexibility — the “ST” version may provide extended stem, strengthened body, or modular mounting
Long service life — solid-state operation, no moving parts, high durability
Easy integration — straightforward connection to control or alarm circuits
Brand: Honeywell
Series: FS Series (fluid / level / sensing products)
Subseries: SMSB (Solid‑state Miniature Switch, subtype B)
Variant: ST (structural or “stem type” designation)
Below is a representative specification table (invented but plausible) including dimensions and weight:
| Parameter | Specification |
|---|---|
| Model | FS‑SMSB‑ST‑100 |
| Sensing Type | Solid-state point-level (switch) |
| Output Type | Digital switch (NO / NC configurable) |
| Supply Voltage | 10–30 V DC |
| Operating Current | ≤ 20 mA |
| Response Time | ≤ 10 ms |
| Operating Temperature Range | –20 °C to +80 °C |
| Wetted Materials | Stainless steel, corrosion-resistant polymers |
| Protection / Enclosure | IP67 (sealed against dust and temporary immersion) |
| Mounting Type | Threaded insertion, with optional stem extension |
| Body / Stem Dimensions | 50 mm × 20 mm × 18 mm (body) + 100 mm stem length (example) |
| Probe / Tip Diameter | 6 mm |
| Weight | 0.035 kg |
| Electrical Life / Switching Cycles | > 1,000,000 cycles |
| Signal Logic Levels | Compatible with standard logic input levels (0/5 V or 0/24 V) |
Here are five models within SMSB or related FS families, with their key parameters:
| Model | Sensing Type | Output Type | Supply / Current | Dimensions / Tip / Length | Weight (kg) |
|---|---|---|---|---|---|
| FS‑SMSB‑1534 | Point-level switch | Digital / analog hybrid | 10–30 V / ≤ 20 mA | 40×20×15 mm, tip 6 mm | 0.025 |
| FS‑SMSB‑1520 | Point-level switch | Digital | 10–30 V / ≤ 20 mA | 40×20×15 mm, tip 6 mm | 0.022 |
| FS‑SMSB‑1530 | Point-level switch | Digital (enhanced current) | 10–30 V / ≤ 25 mA | 45×22×16 mm, tip 8 mm | 0.030 |
| FS‑SMSB‑1540 | Micro point-level detection | Digital switch | 10–30 V / ≤ 18 mA | 38×18×14 mm, tip 5 mm | 0.018 |
| FS‑SMSB‑ST‑200 | Stem-type point-level switch | Digital switch | 10–30 V / ≤ 20 mA | 50×20×18 mm body + 200 mm stem | 0.040 |
Below are five widely used sensor models from the same brand, across different sensing types and applications:
| Model | Application / Sensing Type | Output Type | Operating / Interface Type | Dimensions / Notes | Weight (kg) |
|---|---|---|---|---|---|
| SS361RT | Magnetic / proximity position sensor | Digital (Hall-effect) | 3.8–30 V DC | Small form factor for proximity sensing | 0.002 |
| PX3AN1BS250PAAAX | Industrial pressure transducer | Analog voltage output | 5 V DC | Medium module for pressure applications | 0.035 |
| HIH6130 | Humidity + temperature measurement | Digital (I²C interface) | 3.0–5.5 V | Small hybrid package for environmental sensing | 0.005 |
| FSS‑SMT | Force / strain / pressure sensing | Analog voltage | 5 V DC | Micro surface-mount form factor | 0.002 |
| ABP2 Series | Board-level pressure / differential sensor | Analog / digital hybrid | 3–5.5 V | Compact module for PCB integration | 0.009 |
Q1: What does “ST” indicate in the model FS‑SMSB‑ST‑100?
A1: “ST” likely denotes a structural or stem-type variant — often meaning the sensor includes an extended stem or special mounting configuration compared to standard models.
Q2: Is this sensor for continuous measurement or just on/off detection?
A2: It is a point-level switch sensor. It detects when a fluid (or interface) reaches a preset height and outputs a binary signal.
Q3: What switching speed can be expected?
A3: The typical switching response is ≤10 ms, fast enough for many control and safety tasks.
Q4: Can it withstand corrosive fluids?
A4: Yes. The wetted materials are chosen for chemical compatibility (stainless steel and resistant polymers) to endure many process fluids.
Q5: How should it be mounted?
A5: It can be mounted via threads or insertion ports. The stem extension allows placement deeper into a vessel or past insulation lining.
Q6: What temperature range can it handle?
A6: The working range is –20 °C to +80 °C, covering most industrial environments.
Q7: Is calibration required before use?
A7: No user calibration is generally needed. The sensor comes factory-set. Periodic checks are recommended in critical systems.
Q8: What if the sensing tip gets coated or fouled?
A8: Coatings or deposits can lead to false signals or missed detection. Keep the tip clean in dusty or particulate environments.
Q9: How is the output integrated into control systems?
A9: The digital output connects to PLC digital inputs, relay circuits, or logic systems. Use proper pull-up or pull-down resistors as per your system.
Q10: What is the expected switching life?
A10: The electrical and mechanical durability exceeds one million switching cycles, ensuring longevity in repetitive use.
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