Series-F6-F7-Vertical

Supported Applications

The Dwyer Series F6 and F7 Vertical Level Switches provide simple, inexpensive control of liquid levels within tanks. These hermetically sealed reed switches are actuated by magnets permanently bonded inside a float to open or close a circuit on rising or falling levels. Documented applications include water level monitoring, oil level control, chemical level indication, sumps, stand pipes, tank level control, and high viscosity liquids.

Specific model configurations address distinct service requirements:

• F7-SB: General purpose applications using Buna-N and epoxy/316 SS materials.
• F7-SS2: High temperature, high pressure, and corrosive services utilizing 316 SS (CYC)/316 SS construction.
• F6-SS: Corrosive liquid applications with 316 SS/316 SS wetted materials.
• F7-MPP / F7-MPP-NO: Broad chemical compatibility using Polypropylene/polypropylene components.
• F7-BT: Oils and fuels, featuring Buna-N and epoxy/PBT (Polybutylene Terephthalate) materials.
• F7-PVC: Chemical and plating applications with CPVC/CPVC construction.
• F7-T1: Viscous, sticky, or corrosive liquids using PTFE/TPE wetted parts.
• F7-ST713: Oils, water, and chemicals requiring high-pressure capability up to 750 psi (52 bar).

Operating Conditions & Performance

The series supports a wide range of operating temperatures and pressures depending on the specific model materials. Temperature limits span from -4°F (-20°C) for F6-SS, F6-MHS, and F6-MHS2 up to 392°F (200°C) for the explosion-proof F7-HSS model. Pressure ratings vary significantly by construction: standard models like F7-SB are rated to 150 psi (10 bar), while high-pressure variants such as F7-SS2 reach 450 psi (31 bar) and F7-ST713 reaches 750 psi (52 bar). The lowest pressure rating is found on the F7-PVC model at 15 psi (1 bar).

Electrical ratings are defined by VA, voltage, and amperage limits. For example, F7-SB and F7-SS2 support up to 50 W with a maximum of 200 V (DC or AC peak) or 1.5 A (DC or AC peak). The F6-SS model is rated at 20 VA: 0.08A @ 240VAC. Switch types are SPST hermetically sealed reed switches, reversible for Normally Open (N.O.) or Normally Closed (N.C.) operation.

Minimum specific gravity requirements vary by float design to ensure proper actuation:

• F7-BT: 0.45
• F6-SS and F7-SB: 0.60–0.65
• F7-MPP: 0.90
• F7-HPS: 0.85

Configuration Options

The Series F6 and F7 offer configurable mounting orientations, process connections, wetted materials, and electrical outputs to accommodate diverse installation needs.

Mounting & Process Connections

• F6-SS: Vertical ±20°; 1/8" NPT connection.
• F7 Series (Vertical): Standard mounting includes 1/8" NPT, with specific models like F7-PVC and F7-T1 utilizing 1/4" NPT. The F7-ST713 also uses a 1/4" NPT connection.
• Horizontal Mounting: Models such as F6-MHS/HPS/MHS2 are designed for horizontal mounting with an index arrow pointing up or down, utilizing M16*2 connections (F6-MHS, F6-HPS-11) or 1/2" NPT (F6-HPS-21, 31, F6-MHS2).

Wetted Materials & Construction

The series supports various material combinations to match media compatibility:

• Metallics: 316 SS (CYC)/316 SS, 316 SS/316 SS.
• Plastics & Composites: Polypropylene/polypropylene, CPVC/CPVC, PTFE/TPE, Buna-N and epoxy/PBT, Polysulfone/Polysulfone (F7-HPS).

Electrical Outputs & Connections

• Switch Configuration: SPST or SPDT options available depending on the specific model family.
• Lead Wires: Standard connections include 22 AWG leads with lengths varying by model, such as 18" (45 cm) for F7-SB and F7-SS2, and 24" (61 cm) for F7-MPP, F7-BT, and others. The F6-SS utilizes 20 AWG leads at 11.8" (30 cm).

Approvals & Special Options

• F7-HSS: Explosion-proof rated for Class I, Groups A, B, C, D; Class II, Groups E, F, G; and Class III.
• UL Listed: Specific models including F7-SB* are UL listed.
• Adapters: Accessories such as the A-347 (1/8" x 1-1/4" NPT carbon steel) and A-347-SS (1/8" x 1-1/4" NPT 316 SS) are available for external mounting of vertical models.

Key Product Differences

The Series F6 and F7 differ primarily in their material construction, pressure/temperature ratings, and specific application focus. The F6-SS is a compact stainless steel unit rated for 218 psi (15 bar) at -4 to 257°F (-20 to 125°C), designed specifically for corrosive liquids with a minimum S.G. of 0.65.

The F7 Series expands the envelope significantly:

• F7-SS2: Offers higher pressure capability (450 psi / 31 bar) and temperature resistance up to 300°F (149°C) using cyclically hardened 316 SS.
• F7-ST713: Provides the highest pressure rating in the series at 750 psi (52 bar), suitable for oils, water, and chemicals with a minimum S.G. of 0.80.
• Plastic Models: F7-MPP and F7-PP utilize polypropylene for broad chemical compatibility but have lower pressure limits (100–150 psi) compared to metallic models. The F7-PVC model is limited to 15 psi (1 bar).
• Specialized Floats: Models like F7-T1 use PTFE/TPE for viscous or sticky liquids, while F7-BT uses Buna-N and epoxy/PBT specifically optimized for oils and fuels with a low minimum S.G. of 0.45.

Switch contact behavior varies by model; standard shipping is Normally Open (NO) which closes as the float rises, though specific variants like F7-MPP are configured as Normally Closed (NC).