Professional Installation Guide for NFS22 Series Mechanical Flow Switches‌

Here is the professional English translation of the NFS22 Series Mechanical Flow Switch installation guide:

Professional Installation Guide for NFS22 Series Mechanical Flow Switches‌

I. Pre-Installation Preparation‌

Pipe Section Selection‌

Select horizontal or vertically upward-flowing straight pipe sections (inverted installation PROHIBITED)

Ensure upstream/downstream straight pipe sections ≥5× pipe diameter; avoid turbulence sources (elbows, valves, etc.)

Clean pipeline interior to prevent paddle obstruction

Flow Direction Calibration‌

Confirm medium flow direction strictly matches the arrow indicator on the switch housing

II. Mechanical Installation Procedure‌

Threaded Connection‌ (DN20/DN25 interfaces)

Wrap PTFE thread seal tape or apply sealant to external pipe threads

Hand-tighten the switch into pipe internal threads, then secure with a wrench for additional 1/4 turn (AVOID over-tightening to prevent housing deformation)

Paddle Positioning‌

Paddle axis must be parallel to pipeline centerline

Adjust insertion depth to ensure paddle remains suspended without contacting pipe walls/throttling elements

III. Electrical Wiring Specifications‌

Safety Operations‌

Disconnect power and verify de-energization before wiring

Use ONLY designated equipment grounding terminal for grounding

Terminal Functions‌

Terminal Function Wire Color Example

COM Common Terminal Yellow/Grey

NO Normally Open (flow ON) White/Orange

NC Normally Closed (flow OFF) Black/Blue

▶ Wiring Example‌:

Flow Protection: NO terminal → Equipment start/stop control circuit, COM terminal → Power supply positive

IV. Commissioning & Verification‌

Flow Setting‌

Rotate adjustment knob clockwise to increase trigger flow, counterclockwise to decrease (accuracy: ±2%)

Recommended setting range for fire protection systems: 1~3.5L/s

Functional Testing‌

No-flow Test‌: When flow drops below 10% of setpoint, NC contacts should CLOSE

Full-flow Test‌: When flow reaches setpoint, NO contacts must OPEN immediately (pressure loss ≤0.01bar)

V. Prohibited Actions‌ ⚠️

DO NOT install inverted or with paddle contacting pipe walls

NEVER wire under power or adjust non-calibration screws

AVOID installation near vibration sources (pumps/compressors)

Note: For hydraulic systems, post-installation testing must evaluate lubricating oil film's impact on paddle sensitivity.

(This translation preserves all technical specifications, safety protocols, and industry terminology from the original Chinese documentation.)