High Capacity Line Leak Detectors

The High Capacity MLD product line is based on our standard STP-MLD unit design. The High Capacity MLD’s compact design allows installation in the same containment sump as the submersible pump, greatly reducing the amount of unprotected leak points between the submersible and the MLD.

Order Info
  • Highlights

    Low Line Restriction

    Piston design offers the maximum flow rate possible by keeping flow restriction through the leak detector at an absolute minimum. Piston has a full 41.3 mm of travel to move the leak detector poppet fully out of the flow path when product isbeing pumped.

    Faster Installation

    MLD-HC can be installed after purging air on new installations.

    Piston Design

    Piston cylinder has 94.2 cubic centimeters of volume to help minimize nuisance tripping due to thermal contraction during cold weather.

    MLD-HC Seal

    Threads seal using O-rings instead of thread sealant. This seal design makes for simple installation and removal of MLD-HC without large wrenches in the tight working environment of the containment sump.

  • Specs

    • Detects leaks of 44.4 lph or greater at 0.69 bar.
    • Third party evaluated to comply with US EPA requirements 280.41 (B) and 280.44 (A) for continuous monitoring of pressurized piping.
    • Size: 7¾" × 15" (197 mm x 381 mm).
    • Weight: 28 pounds (12.7 kg).
    • The MLD-HC will remain in the open flow position with dynamic line pressure at 0.14 bar at the outlet.
    • Maximum static head pressure without affecting operation is 12' (3.7 m) from MLD-HC to dispensing point.
    • Minimum height required from 3" (76.2 mm) NPT port centerline for top clearance is 9½" (241 mm). Not position sensitive. Can be installed horizontally to reduce clearance to 3" (76.2 mm).
    • Compatible with all blends of motor fuels including alcohol blends from 0 to 10% ethanol, 20% MTBE or ETBE with 80% gasoline, or 17% TAME with 83% gasoline as well as diesel, fuel oil, Avgas, jet fuel or kerosene.
    • Two models available: STP-MLD-HC for gasoline, STP-MLD-HCD for diesel.


    • Consult factory for applicable approvals.

    Quality Certification

    • Franklin Fueling Systems is an ISO 9001 Certified Manufacturer.
  • Order Info

    401315902STP-MLD-HC leak detector complete with Adapter "T" (for gasoline)
    401320902STP-MLD-HCD leak detector complete with Adapter "T" (for diesel)
    401315901Replacement high capacity leak detector ONLY (for gasoline)
    401320901Replacement high capacity leak detector ONLY (for diesel)
    401316930Replacement cover assembly
    401325901Replacement Adapter “T” with cover assembly
    400449902MLD-HC hardware pack, includes fittings and documentation
    • Refer to high capacity MLD installation manual for complete fuel compatibility specifications.
    • 1. MLD-HC models are listed for compatibility with fuel mixtures containing up to 10% ethanol with gasoline, diesel fuels, and 20% MTBE, 20% ETBE, or 17% TAME with gasoline.
    • 2. MLD-HCD models are listed for compatibility with diesel fuels and kerosene applications only.
    • 3. All above models will only mount in Adapter "T" (p/n 401325901)
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