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Brand: Veeder-Root
Veeder-Root Interstitial Sensor for Steel Tanks 0794390-420
Description
Interstitial sensor for the annular space of double-wall steel tanks
The Veeder-Root Interstitial Sensor for Steel Tanks is a non-discriminating sensor that detects liquid between the double walls of a steel tank. It is listed as part number 0794390-420 with a 16 ft (4.88 m) cable and 0794390-460 with a 30 ft (9.14 m) cable, and it reports to a Veeder-Root console as a leak alarm if liquid enters the annular space.
The sensor is small, 2.5 in tall and 1.5 in in diameter, and works with a reed switch and float. It must rest on the bottom of the interstitial riser, and the datasheet shows the cable run through the riser to a weatherproof junction box, seal-off and rigid conduit to the console. A 2 in (50 mm) riser cap and adapter kit, 0312020-928, is available separately.
Technical specifications
Values come from the Veeder-Root sensor specification P/N 577013-750-14 Rev. AF (2025). The sheet prints the part numbers as 0794390-420 and -460 in the Part Number line and as 0794380-420 and -460 in its Notes line; this page uses the Part Number line.
| Parameter | Specification |
|---|---|
| Product / part numbers | Veeder-Root Interstitial Sensor for Steel Tanks: 0794390-420 with 16 ft (4.88 m) cable; 0794390-460 with 30 ft (9.14 m) cable |
| Category | Non-discriminating; senses liquid in the space between the double walls |
| Principle | Reed switch and float |
| Trip height | 1.4 in (3.56 cm) |
| Alarm messages | Normal; fuel alarm when liquid is detected; sensor out when it stops communicating |
| Temperature range | -4 to +140 °F (-20 to +60 °C) |
| Size | 2.5 in (6.4 cm) high by 1.5 in (3.8 cm) in diameter |
| Riser kit | 0312020-928, 2 in (50 mm) interstitial sensor riser cap and adapter (separate order) |
| Supported consoles | TLS-450PLUS and TLS-450 (software 6.A and 4.A or higher), the TLS4 family (6.A or higher), TLS-350/R/PLUS (124/324 or higher), TLS-350J and TLS-300i |
| Input hardware | USM 0332812-001; USIOM-AC 0330020-750 / -751; interstitial sensor module 0329358-001; probe/sensor modules 0329356-003 and 0330230-001 |
| Manufacturer warranty | One year parts and labour with the system; one year parts only if bought separately |
How to use the sensor in a double-wall steel tank
Double-wall steel tanks have a sealed annular space between the inner and outer shells. Placing the sensor at the bottom of the interstitial riser lets it detect liquid collecting in that space. The datasheet classes it as non-discriminating, so it raises a liquid alarm without identifying the liquid.
The sensor rests in the riser; the example drawing shows a reducer with a 1/2 in NPT opening for the cable cord grip and the leader cable running up the riser. The fuel compatibility matrix and typical locations are shown in the datasheet as a checklist, so confirm the liquid you expect against the PDF.
What to confirm before ordering
- Console and software version, plus a free sensor input or the interstitial interface module.
- Cable length: 16 ft or 30 ft, based on the riser to junction box distance.
- Riser size, because a 2 in riser cap and adapter kit is sold separately.
- The part-number print difference in the datasheet (0794390 versus 0794380 in the Notes line), which we will confirm when quoting.
Documents and quotation
The Veeder-Root specification sheet for the steel-tank interstitial sensor is attached to this page as a PDF. Send us the tank type, riser details, console and cable length needed and we will prepare a quotation. Seven Star LLC is an independent supplier in Muscat; price and lead time are confirmed per RFQ. This sensor is filed under our level instrumentation category, the nearest leaf for liquid detection.
See also: Veeder-Root TLS-350PLUS Automatic Tank Gauge (Legacy Console).
Datasheets & Documents
- Datasheet Veeder-Root Interstitial Sensor for Steel Tanks specification (P/N 577013-750-14 Rev. AF) Download
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About brand
Veeder-Root is an American supplier of automatic tank gauging and fuel management systems for service stations and fuel depots. The company was formed in May 1928 by the merger of Curtis Veeder's Hartford counter business, started in 1895, with the Root company of Bristol, Connecticut. A counter fitted to a gasoline pump in the early 1930s took Veeder-Root into the petroleum industry. Today it is part of Gilbarco Veeder-Root, a Vontier company.
Seven Star LLC is an independent supplier in Muscat. We list Veeder-Root consoles, probes and sensors from the maker's published datasheets for fuel stations, depots and airports in Oman and the GCC.
Veeder-Root company profile
| Founded | May 1928, Connecticut, USA, by the merger of Veeder Manufacturing (1895) and the Root company |
|---|---|
| Headquarters | Simsbury, Connecticut, USA |
| Ownership | Vontier, through Gilbarco Veeder-Root |
| Installed base | Tank monitoring in more than 500,000 underground storage tanks, according to the company |
| Product families | TLS-450PLUS and TLS4 automatic tank gauges, Mag Plus magnetostrictive probes, leak and interstitial sensors, line leak detectors, submersible turbine pumps (Red Jacket) and fuel management software |
Milestones
- 1895: Curtis Veeder starts Veeder Manufacturing in Hartford.
- 1928: Veeder and Root merge to form Veeder-Root.
- Early 1930s: Veeder-Root counters are fitted to gasoline pumps, starting its petroleum business.
Veeder-Root product series
Tank gauge consoles include the TLS4 and the non-expandable TLS4B, the TLS-450PLUS and the legacy TLS-350PLUS. Mag Plus in-tank probes are offered for gasoline and diesel, jet fuel, LPG and light and heavy oil, and Mag-FLEX probes cover tall tanks. Leak detection sensors include the discriminating containment sump sensor 0794380-352 and the interstitial sensor 0794390-420 for double-wall steel tanks. The EMR4 electronic meter register is used on fuel delivery trucks.
Where Veeder-Root products are used
Petrol stations, fuel depots, airports and fleet fuelling sites, where the system measures product level, water and temperature in underground and aboveground tanks, monitors sumps and interstitial spaces and supports inventory reconciliation and leak tests.
Veeder-Root products we list
Ordering Veeder-Root products: what we need
Send the console model and the modules installed, the number of tanks, the product in each tank, the tank type and diameter for probe length, and the sensors required. Where a model is discontinued, we say so on the product page and confirm the successor before quoting.
Facts checked against Veeder-Root's company overview and published company histories, October 2026.
Browse Veeder-Root products by category: Level Instrumentation.
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Frequently Asked Questions
What does this sensor detect?
Liquid between the double walls of a steel tank; it is non-discriminating so it does not identify the liquid.
Which cable lengths are available?
16 ft (4.88 m) for 0794390-420 and 30 ft (9.14 m) for 0794390-460.
How does it work?
A reed switch and float detect liquid at a 1.4 in (3.56 cm) activation height.
How large is the sensor?
2.5 in (6.4 cm) high and 1.5 in (3.8 cm) in diameter.
Which consoles support it?
TLS-450PLUS, TLS4 series, TLS-350 series and TLS-300i, with minimum software versions in the datasheet.
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