Safiery STLPO02 compact external-pressure tank level sensorCompact bottom-fitting pressure sender, 0–5V, IP65, 2m lead

Overview

STLPO02 is Safiery's compact pressure sender for fresh-water tanks, fitted from outside at the bottom of the tank through a G1/4in port. A piezo-resistive ceramic cell in a 316 stainless steel body converts the water column, 0–500mm on its datasheet, into a 0–5V signal from a 12V DC supply, with 1.5–2% full-scale accuracy and a response time of 10ms or less. It weighs 0.1kg, has a 2m waterproof PE lead and suits a Victron GX Tank 140 or a Simarine ST107 voltage input.

• Pressure senders with 0–5V output and 12V DC supply
• External bottom-fitting and submersible IP68 versions
• Wema-style stainless float senders on SAE 5-hole flange
• Voltage senders connect to a Victron GX Tank 140
• Simarine ST107: 4 resistive and 3 voltage inputs
• 2-year warranty on pressure sensors and Simarine products

Sender types

The pressure senders measure the weight of the liquid column with a piezo-resistive ceramic cell behind a stainless steel diaphragm and turn it into a 0–5V signal from a 12V DC supply. STLPO01 and the compact STLPO02 screw into a fitting at the bottom of the tank from outside; the STLPS01 submersible sender hangs inside the tank on its sealed cable and is rated IP68 for drinking water.

Wema-style senders work mechanically: a float carrying magnets slides along a stainless steel tube and closes reed switches inside it, giving a resistance that falls from 240Ω to 33Ω in steps of 21mm. The float is the only moving part, the senders suit fuel, oil and water, and they bolt onto the standard SAE 5-hole pattern in 200, 400 or 450mm lengths.

Connecting to Victron and Simarine

Voltage-output senders connect to a Victron GX Tank 140, which reads up to four 0–10V sensors; lower and upper limits are set on the GX for a 0–5V signal, together with fluid type, tank shape and an averaging time of 1–60 seconds. Channels 3 and 4 supply 24V to the sensor, channels 1 and 2 pass on an external supply. Safiery wires its resistive Wema senders directly to a Cerbo GX or a Simarine monitor.

On Simarine systems the ST107 module adds four resistance inputs for 0–65kΩ senders or NTC temperature probes and three voltage inputs for voltage senders or voltage-only batteries. It links to a PICO display over SiCOM, where each sender is calibrated, and offers a programmable 1A alarm contact.

Installation notes

External pressure senders need a threaded G1/4in port at the bottom of the tank, while the submersible type is lowered into the tank on its cable. Safiery recommends shielded sensor cable with the shield bonded to bare metal of the vehicle or boat. Every sender has to be calibrated on the display it reports to. The ST107 belongs in a clean, dry place; SiCOM runs of 5m or more need 2×2×0.25mm² twisted pair.

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