The Yoshitake SB-1F is a ball type sight glass designed for cold and hot water applications. It allows users to check the fluid flow by observing the movement of the synthetic resin balls inside the hardened glass window. This product features a ductile cast iron body with JIS 10K FF flanged connections. The inner surface of the glass is kept relatively free of water scale due to the rolling action of the balls against it.

Features

• Flowing state of fluid can be checked with the movement of the balls inside the sight glass.
• Inner surface of the glass is less liable to water scale because the rolling balls contact the surface.
• Compact, lightweight, and space-saving design.
• Can be connected to horizontal or vertical piping (glass part should face sideways).

Specifications

Specification	Value
Model	SB-1F
Type	Ball
Application	Cold and hot water
Maximum Working Pressure	1.0 MPa
Temperature Range	5–85°C
Connection	JIS 10K FF flanged

INFO

Glass parts and balls are consumable parts. 15A-25A sizes use three colored balls (Red, White, Blue). 32A-50A sizes use three colored balls (Red, White x2).

Parts and Materials

Part Name	Material	Standard
Body	Ductile Iron	FCD450
Cover	Ductile Iron	FCD450
Glass	Tempered Glass	-
Gasket	Non-Asbestos	-
Ball	Synthetic Resin	PE, PP, MA
Ball Casing	Stainless Steel	SUS304

Dimensions and Weights

Nominal Size	d (mm)	L (mm)	W (mm)	Flange D (mm)	Flange C (mm)	Weight (kg)
15A	15	130	35	95	70	2.2
20A	20	130	35	100	75	2.6
25A	25	150	44	125	90	4.1
32A	32	160	57	135	100	5.9
40A	40	170	57	140	105	6.2
50A	50	200	73	155	120	9.5

Minimum and Maximum Flow Rates

For water applications, the table below defines the flow rate requirements. The minimum flow rate is the lowest flow required to start moving one or more balls. The maximum flow rate is when the flow velocity reaches 2 m/s.

Nominal Size	Min. Flow Rate (m³/h)	Max. Flow Rate (m³/h)
15A	0.6	1.5
20A	0.7	2.6
25A	0.8	4.3
32A	1.6	7.2
40A	2.0	9.8
50A	2.5	15.8

INFO

Pressure loss at the maximum flow rate is 0.05 MPa. Flow rates exceeding the maximum limit will accelerate ball abrasion.

Installation and Operation

Piping Example (Cold and Hot Water)

WARNING

1. Before connecting the product, remove foreign substances and dirt inside the piping to prevent glass damage or opacity.
2. Check the direction of the product so that the fluid flowing and the arrow marked on the product are in the same direction.
3. Do not apply excessive load, torque, or vibration to the product to avoid leakage.
4. Do not retighten the cover of the product while under pressure.
5. Do not apply a rapid temperature change during operations.

Required Space for Disassembly

Nominal Size	A (mm)	B (mm)
15A-25A	30 or more	100 or more
32A-40A	35 or more	120 or more
50A	40 or more	150 or more

Troubleshooting

Trouble	Cause	Remedy
Balls do not move	1. Balls are caught by foreign substances on the glass. 2. Balls are caught by scratches on themselves or the glass. 3. Flow rate is below the minimum limit. 4. Fluid does not flow. 5. Installed in opposite direction.	1. Disassemble and clean to remove substances. 2. Disassemble and replace damaged parts. 3. Use a nominal size matching the flow rate. 4. Check piping. 5. Reinstall in the correct direction.
Fluid flow cannot be observed	1. Foreign substances on glass or glass is stained. 2. Inner surface of glass has erosion or scratches.	1. Disassemble and clean the product. 2. Disassemble and replace the glass.

Maintenance: Disassembly and Reassembly

DANGER

Completely discharge the pressure inside the product, piping, and equipment prior to disassembly and inspection. When the fluid is hot, cool down the product to a condition where it can be touched with bare hands.

Disassembly

1. Remove the bolts, nuts, and spring washers (for 15A-25A only) using spanners.
2. Take out gaskets, glasses, and covers.
3. Take out all the balls from the casing. Be careful not to lose the balls when detaching the glass.

Reassembly

1. Put the balls into the ball casing, and then attach the gaskets, glasses, gaskets, and covers in this order to the body.
2. Temporarily tighten the covers to the body with bolts, spring washers, and nuts. Then tighten them evenly at the specified torque using a torque wrench.

Nominal Size	Tightening Torque
15A, 20A	7 N·m
25A	10 N·m
32A, 40A	15 N·m
50A	25 N·m

INFO

• The glasses and gaskets are consumable parts. Replace gaskets with new ones during reassembly. Replace glass if eroded by more than 10% of its thickness or scratched.
• Replace the balls when their diameter becomes 5 mm or less (for 15A-25A) or 7 mm or less (for 32A-50A).