TLV T8N / T10N and TF8N / TF10N are lightweight cast iron sight glasses designed for installation at the outlet side of steam traps to monitor trap performance and check for steam leakage. They are also recommended for checking the line flow of air and water, and are suitable for small-to-large flow rates.

Features

1. Clear sighting through self-polishing, heat-resistant glass.
2. Ball movement indicates the flow status.
3. Model T(F)10N is designed for large flow rates due to through-hole in the partition between inlet and outlet.
4. Compact design saves space.
5. Inline repairable.

Configuration

INFO

Construction of the T(F)10N(L) differs from that of the T(F)8N(L) only in that there is a through-hole in the partition between the inlet and outlet, making them suitable for use with large flow rates.

No.	Description	Repair Kit
1	Body
2	Sight Glass	✓
3	Glass Holder
4	Ball	✓
5	Gasket	✓
6	Nameplate
7	Guard Plate	✓

Specifications

Model	T8N / T10N	TF8N / TF10N
Connection	Screwed	Flanged
Size (DN)	1/2", 3/4", 1", 1 1/4", 1 1/2", 2"	DN 15, 20, 25, 40, 50
Maximum Operating Pressure (barg) PMO	13	13
Maximum Operating Temperature (°C) TMO	200	200
Applicable Fluids	Steam, Water, Air	Steam, Water, Air

WARNING

Do not use for toxic, flammable or otherwise hazardous fluids. Maximum Allowable Pressure (PMA): 13 barg. Maximum Allowable Temperature (TMA): 200 °C. These are pressure shell design conditions, not operating conditions. Contact TLV for optional models T8NL/TF8NL/T10NL/TF10NL up to 150 °C.

No.	Description	Material	DIN	ASTM/AISI
1	Body	Cast Iron FC250	0.6025	A126 Cl.B
2	Sight Glass	Heat-resistant Tempered Glass	-	-
3	Glass Holder	Cast Iron FC250	0.6025	A126 Cl.B
4	Ball	Fluorine Resin PTFE	PTFE	PTFE
5	Gasket	Fluorine Resin PTFE	PTFE	PTFE
6	Nameplate	Stainless Steel SUS304	1.4301	AISI304
7	Guard Plate	Mica	-	-

Dimensions

T8N / T10N Screwed

TF8N / TF10N Flanged

Install a check valve on the outlet side if there is the danger of downstream water hammer!

Capacities

1. Capacities are based on continuous discharge of condensate 6 °C below saturated steam temperature (or continuous discharge of water at room temperature if so stated).
2. Differential pressure is the difference between the inlet and outlet pressure of the sight glass.

Installation & Operational Check

1. Before installation, be sure to remove all protective seals.
2. Before installing the product, blow out the inlet piping to remove any piping scraps, dirt and oil. Close the inlet valve after blowdown.
3. Install the product so the arrow on the body is pointing in the direction of flow.
4. Install on horizontal piping with the glass portion facing up.
5. Connect the outlet piping.
6. Open the inlet valve and check to make sure that the product functions properly.
7. As sight glasses deteriorate with use, they should be replaced annually to ensure safety.

Operational Check:

• Normal: When condensate is present, the ball floats. (The sound of flow can be heard.) For T10N/TF10N, when the flow of condensate is light, the sound of flow can be heard but the ball may not float.
• Failure: Fluid leaks to the outside of the product, the ball is not visible or the ball does not float.

Inspection & Maintenance

Operational inspections should be performed at least twice a year, or as called for by the operating conditions.

Part	Inspection
Gaskets	Check for warping or damage
Glass	Check for fractures or cracks
Guard Plate	Check for fractures or cracks
Ball	Check for deformation

Tightening Torque:

• Glass Holder: 120 N·m (Distance Across Flats: 60 mm)

Troubleshooting

Problem	Cause	Remedy
Cannot see through glass (Ball not visible)	The glass is dirty; Guard plate is dirty; Build-up of dirt inside the body	Clean glass / guard plate / body
Liquid leaks to the outside of the product	Deterioration or damage to gaskets; Improper glass holder tightening torque; Glass or guard plate damaged	Replace gaskets / glass / guard plate; Tighten to proper torque
Glass becomes damaged	Operating pressure or temperature exceeds maximum specified conditions; Glass outlived service life	Compare specs and actual conditions; Replace glass
Ball does not move (T8N/TF8N)	Body is clogged with dirt, or build-up on the ball	Clean parts