| Valves and Fittings Information
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304 vs 316L stainless steel.
304 stainless steel is suitable for food industries. 316L is typically requested
by pharmaceutical, chemical, and semiconductor sectors. 316L (low carbon) stainless
steel is more corrosion resistant than 316 or 304.
Important Specifications
- Material---304 stainless
- Contact Surface (Inside) Finish
- Valves : 240 grit or better inside.
- Fittings : 180 grit or better inside.
- Wall thickness
(wall thickness is a standard. This ensures compatibility of valves and fittings from different
manufacturers)
- 0.065"
for sizes up to 3"
- 0.083" for 4"
- 0.109" for 6" and
8"
- How to Determine TriClamp Size
- Explanation of Hose Barb OD
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Mechanical Polish
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RA micro-inch
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RA micron
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ISO designation
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150 grit
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32
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0.8
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N6
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180 grit
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20
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0.5
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---
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240 grit
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15
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0.4
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N5
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320 grit
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8
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0.2
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N4
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There are a several designations of surface finish. (They originate with
different organizations).
- RA is "Roughness Average". The smaller the number, the smoother
the surface.
- Grit refers to the type of material used to polish (like sand paper).
The larger the grit number, the smoother the finish.
- ISO is organization with standards similar to 3A (US dairy industry)
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Some practical comparisons of Ball and Butterfly valves
- Sanitation
Butterfly and Diaphragm valves are the only "true" sanitary valves.
All surfaces can be cleaned with the valve open. On the other hand, Ball Valves
have a void between the ball and the outer wall that cannot be cleaned directly.
There are several approaches to mitigate this for food use. Drains are added
to empty this void. 'Fully Encapsulated' ball valves fill this void with the
sealing ball itself (the surface between the sealing ball and the outer wall
still cannot be cleaned directly).
- Opening Torque
Butterfly valves are much easier to open than Ball Valves. Fully Encapsulated
ball valves are more difficult to open than standard ball valves. The larger
the valve, the more torque required. Actuators, in addition to automation applications,
can be used to easily open large valves.
- Throughput
Butterfly Valves partially occlude the throughput while ball valves have no
occlusion when fully open.
- Weight
Ball Valves are much heavier than Butterfly Valves.
- Pressure and Temperature Ratings
Ball Valves with PTFE (teflon) seals have both higher temperature and pressure
ratings than Butterfly Valves. However, the pressure and temperature ratings
of Butterfly Valves are sufficient for all wine industry applications.
- Price
Ball Valves are generally more expensive than Butterfly Valves because they
use more steel (hence they are also heavier).
Butterfly Valve Handles
- 'Pull' vs 'Push (Trigger)' handles. There are two general designs for handles
on butterfly valves. 'Pull' handles are first pulled straight out away
from the valve, then you turn the handle. 'Push' handles require pushing
the handle down followed by the twist. Trigger handles are a type of
push handle.
- Pull handles lock in fully-open, fully-close, and half-open.
- Trigger handle has 12-locking positions in 180°