Series-F7-MQConfiguration

Supported Applications

The Dwyer Series F7-MS and F7-MQ Multi-Station Level Switches are designed for vertical installation in tank tops (mounting up) or tank bottoms (mounting down). These switches operate normally with inclinations up to 30° from the vertical axis. The series is intended for liquid level applications requiring specific gravity thresholds of .55 to .75, depending on float material and mounting type.

Integrated temperature sensor options are available: a thermistor provides continuous indication (10,000 ohms @ 77°F / 25°C), while a thermostat option offers switch action with settings from 150°F to 175°F. For hazardous area applications involving ignitable mixtures or combustible dust, the use of an appropriate explosion-proof enclosure or intrinsically safe interface device is required.

Operating Conditions & Performance

The series supports process temperatures ranging from -40°F to +300°F (-40°C to +148.9°C) for 316 Stainless Steel floats, and up to 180°F (82.2°C) with water or -40°F to +230°F (-40°C to +110°C) with oil for Buna N floats. Pressure ratings vary by configuration: 150 psi is standard for Buna N floats on Mounting Types 1, 2, and 3; 750 psi (for Mounting Type 5 with 316 SS housing and stem); and up to 750 psi for 316 Stainless Steel floats on Mounting Types 1, 2, 3.

Switch ratings include SPST configurations rated at 20 VA or 100 VA, and SPDT configurations rated at 20 VA. Specific load limits are .17 A @ 120 VAC for both switch types. The switches feature excellent repeatability with an actuation level tolerance of ±1/8" when calibrated on descending fluid levels using water.

Key Performance Limits

• Temperature: -40°F to +300°F (-40°C to +148.9°C) for 316 SS; Water: To 180°F (82.2°C); Oil: -40°F to +230°F (-40°C to +110°C).
• Pressure: Up to 750 psi with 316 Stainless Steel floats; up to 150 psi with Buna N floats.
• Inclination: Vertical ±30°.

Configuration Options

The series offers extensive configurability across mounting types, float materials, and electrical outputs. Mounting Types 1 through 5 accommodate various process connections including 1/2" NPT, 1-1/4" NPT, 2" NPT, 3" 150# Flange (Type 4), and external mount configurations with 2-5/8" FNPT or 2-1/4"-12 UNF-2A threads.

Mounting Types & Dimensions

• Type 1: 1/2" NPT, Max. Length (LO) 36", Brass or 316 SS stem/mounting.
• Type 2: 1-1/4" NPT, Max. Length (LO) 60", Brass or 316 SS stem/mounting.
• Type 3: 2" NPT, Max. Length (LO) 140", Brass or 316 SS stem/mounting.
• Type 4: 3" 150# Flange, Carbon Steel or 316 SS flange with 316 SS stem, Max. Length (LO) 140".
• Type 5 (External Mount): Brass housing/stem or 316 SS options, Max. Length (LO) 120".

Float & Switch Options

• Float Materials: Buna N (Min. s.g. .75; .55 for Type 1, 3, 4, 5) or 316 Stainless Steel.
• Switch Types: SPST or SPDT configurations with NO/NC options.
• Float Stops: Beryllium Copper Grip Rings (Brass units); S.S. ARMCO PH-15-7MD Grip Rings (Stainless Steel units). Units greater than 72" overall length are supplied with collars and setscrews instead of grip rings.
• Electrical Connection: #22 AWG, 24" L., Polymeric leads; Junction box for wire leads available as NEMA 4 (not available with connection type 1).

Actuation Level Spacing

The series supports up to four control points. Minimum spacing requirements include: A = 1-1/2" from actuation point to bottom of mounting; B = 3" between actuation levels; D = 2" from end of unit to lowest actuation level.

Key Product Differences

The Series F7-MQ Quick-Ship configuration allows for customized stem lengths up to 72" (1.82 m) and specific set point distances defined in the model number guide (e.g., L4, L3, L2, L1). The series distinguishes between float types: F1 (Buna N), F2 (Buna N or 316 SS), and F3 (316 Stainless Steel only).

Material variations affect pressure ratings significantly. Buna-N floats are limited to 150 psi, whereas 316 Stainless Steel floats support up to 750 psi on compatible mounting types. The Series F7-MS manual covers the broader family including Type 4 flange mounts and external mount configurations (Type 5), while the F7-MQ data sheet focuses on quick-ship variants with stem lengths capped at 72".

Wiring color codes differ by switch group: SPST Group I uses Black for Common, Yellow/Blue/Brown/Orange/Gray for L3-L6; SPDT configurations utilize White/Yellow or White/Blue combinations depending on the specific wiring diagram (Group III or IV).