What is an Iris Valve?
Guest article by Kevin Peterson of Salina Vortex
 Iris
valves control the discharge of free-flowing, dry material in
gravity flow applications. Most typically, they are located on
bulk-bag discharge stations, portable and fixed bin bottoms and
chutes.
The valve mechanism consists of two
concentric rings connected by a flexible, tubular sleeve material.
One end of the sleeve is fixed inside the valve body. The other end
is attached to a control ring that is normally manipulated by an
external handle. As the handle is rotated through a 180º arc, the
sleeve is twisted to the point that it becomes a flat, tight solid
barrier.
The sleeves for Iris valves are
available in a variety of fabrics, coated fabrics and rubber
material to accommodate a range of material handling requirements.
The use of double sleeves is common for handling fine powders.
Rubber material is regularly used to handle abrasive materials, or
when wash-down is likely to occur.
Iris Valve Closing
The bodies of Iris valves are
typically aluminum, but stainless steel bodies are also readily
available. Anodized or Teflon coated aluminum bodies are offered as
options.
 Manually
actuated Iris valves are available in two styles. The twist-handle
style allows infinite opening control. The quick-lock handle, with a
limited number of set points on the valve body, allows quicker
action to reach those set points.
Two bolt hole mounting patterns for
each size of valve are offered as standards. Mating spool pieces and
ferrule type connections are also available.
Typical material handled by the Iris
valve ranges across most industries, including: chemicals, dairy,
food, minerals, plastics and pharmaceuticals. Iris valves are often
used to handle friable products because of their gentle closing
action. Many companies utilize Iris valves as a means of shutting
off material being discharged from bulk bags.
Iris Valve Pros
- Inexpensive
- Compact design and weight of the valve make it easy install,
especially in confined areas.
- Ideal for use with delicate products.
- Unobstructed orifice
- The valve closes to the center of the valve, allowing containers
to be filled more evenly.
- Easy to maintain
Iris Valve Cons
- Not recommended for handling large
volumes of material.
- Not for use with heavy, abrasive material.
- Valve cannot close through a standing column of material.
- Valve body will not support heavy equipment hanging from it.
- Bolt hole mounting patterns
differ and are usually specific to the
manufacturer.
Other Considerations
 Iris valves are subject to torsional
stress, especially as they are being closed. Handles and
locking mechanisms made of polycarbonate are subject to distortion
and breakage. Polycarbonate control rings are subject to the
same problems.
Additionally, iris valves containing
bronze control rings are subject to metal flaking inside the valve
due to the metal-on-metal contact between the bronze control ring
and the metal valve body. This can lead to damaged sleeves,
introduction of foreign material and erratic actuation of the valve.
It is important to thoroughly investigate materials of construction
prior to making a purchase.
Comments, Suggestions and More!
If you would like to comment on the
article or discuss iris valves and their design, please feel free to
click the link below and post your comments. Its a great way to let
our author know what you think about his article! Add your comment
to our discussion about it in our Help Forum, click this link:
http://www.powderandbulk.com/cgi-bin/yabb/YaBB.pl?board=general;action=display;num=1116704538
About our author
Kevin Peterson is Director of
Marketing for Salina Vortex Corporation. Salina Vortex is a
manufacturer of precision iris valves in 4” through 18” sizes.
For further information, contact:
Mr. Kevin Peterson
Salina Vortex Corporation
3024 Arnold Avenue
Salina, Kansas 67401
Telephone: 785.825.7177
Web site:
www.salinavortex.com
Help others by posting your comments, suggestions and
experiences with bulk solids feeding or any other materials handling concerns you may have
on our On-Line Help Forum.
For
past Ask Joe ! Articles, visit the Ask Joe! Archived Articles.
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