A flange mounted pig detector is an intrusive, bidirectional pig signaler that bolts to a 2 inch ANSI B16.5 flange and indicates passage with a flag or switch. EMT’s SN2-TQZ covers Class 150 to 2500 and needs no power for the flag type.
Introduction
A flange mounted pig detector is the right call when you cannot or will not weld a base to the line. EMT fits the SN2-TQZ onto a matching flange at the launcher, receiver or a mid-line tap, and the trigger reaches into the bore. When the pig passes, the flag stands up or the switch closes. Because the flange matches the pipe class, the fitting carries the same pressure as the line.
Flange And Class
The detector uses a 2 inch flange built to ANSI B16.5, with pressure class from 150 to 2500. The flange face to pipe inner wall distance is a custom dimension per order, so EMT needs the stand-off before shipping. RF facings take a 3.2 or 4.5 mm spiral wound gasket; a ring joint takes a 3 mm metal gasket.
Indicator And Output
Type B is the manual-reset flag. Type C adds an SPDT or DPDT switch that holds its state and needs no supply of its own. The switch wiring uses three leads: common, normally open or closed, and ground. Contact rating is 3A at 24V DC, and the conduit thread is 1/2 NPT. The switching output can drive a relay, a controlled device or an upstream signal.
Trigger Direction
For the bidirectional type, the trigger must point along the flow. EMT straddles the trigger support across the pipe centreline so the pig trips it from either direction. After fitting, you can turn the flag head clockwise to face the viewing angle you want without disturbing the seal.
Maintenance
If you see leakage at the flange seat, the seal has failed and the unit comes off for service. Keep the mating flange to ANSI B16.5 or the agreed custom standard so the bolt holes line up on site.
Key Features
- 2 inch ANSI B16.5 – Matches the pipe flange, no weld needed.
- Class 150 to 2500 – Carries the line pressure class.
- Bidirectional trigger – Trips in either flow direction.
- Switch option – SPDT or DPDT, no power required.
- Field adjustable head – Turn the flag to the best viewing angle.
- Serviceable – Seals return for rebuild, flange seat replaceable.
Specifications
| Attribute | Value |
| Model | SN2-TQZ (flange mounted) |
| Flange | 2 inch, ANSI B16.5 |
| Pressure class | Class 150 to 2500 |
| Type | Intrusive, bidirectional trigger |
| Displays | B flag / C flag+switch |
| Switch | SPDT or DPDT, 3A / 24V DC |
| Conduit | 1/2 NPT |
| Seal | RF gasket 3.2/4.5 mm, RTJ 3 mm |
FAQ
Do I need to weld this detector?
No. It bolts to a prepared ANSI B16.5 flange of the same class, which is why operators pick it when a shut-down for welding is hard to schedule.
What flange data does EMT need?
The stand-off from flange face to pipe inner wall, the class, the facing type and the bolt pattern. Those set the custom base height before shipment.
Can the switch drive my PLC alarm?
Yes. The C-type SPDT or DPDT output is passive, rated 3A at 24V DC, and wires to a relay, a device or an upstream signal with common, NO or NC, and ground.
Reviews
There are no reviews yet.