HESCO ProactiView on Flow Control Gates
Keywords: Sluice Gates, Slide Gates, Flow Control, Cast Iron vs. Fabricated
Sluice and slide gates have been used for water flow control for hundreds of years. A few years ago, the venerable cast iron sluice gate was challenged by a fabricated sluice gate for use in submerged, high-head flow control conditions. Ultimately, cast iron won out to remain the champion for that application. Fabricated slide gates constructed of aluminum or stainless steel had been used successfully to control flow in open channels, and there are several important reasons why they should continue to be used in this way. This issue of ProactiView will shed some light on the design differences of the Cast Iron Sluice Gate and the Fabricated Slide Gate to provide guidance on the appropriate uses of each.
Contents
Cast Iron Sluice Gates Overview
Fabricated Slide Gates Overview
Comparison of Seating Methods
Overall Comparison of Cast Iron and Fabricated Gates
Follow up with HESCO Regarding Flow Control Gates
ADDITIONAL NOTE on Chlorine Feed Systems
Reward for Best Suggestions
Cast Iron Sluice Gates Overview
A sluice gate is a cast iron, vertically sliding valve with bronze seating surfaces and adjustable bronze wedges. It is used at the end of a pipe line or to cover an opening in a wall and is not an in-line valve. Sluice gates are raised and lowered by means of a stem or rod, using a manually operated screw stem hoist, an electrically driven screw stem hoist, or a hydraulic cylinder. Sluice gates are mounted to a pipe flange, to a wall casting or thimble embedded in the concrete or directly to the concrete wall with anchor bolts.
These gates are primarily designed to handle high seating or unseating heads and less frequent cycles of operation. Unlike their fabricated counterparts, the cast iron sluice gate is extremely rigid and is machined flat to a very high tolerance. The rigidity of the disc, combined with the machined seating surfaces, allow for the gate to be extremely reliable under a variety of conditions including high heads and imperfect installation practices.
Fabricated Slide Gates Overview
A Fabricated Slide Gate can be made of carbon steel, stainless steel or aluminum. Like their sluice gate counterparts, they are raised and lowered by means of a stem or rod, utilizing the same actuation methods previously mentioned. Fabricated slide gates are frequently used for open channel flow control either in the middle of the channel, or mounted at the end of the channel. The frames can be either embedded or mounted in the channel wall. Fabricated Slide Gates are intended and designed for more frequent operation. They are often used for throttling service
Fabricated gates that are used as sluice gates are prone to experience problems in higher head applications for two main reasons
Cast Iron Sluice Gates use a bronze-to-bronze wedge seal that is designed to hold large amounts of head pressure without leaking. As the sluice gate closes, wedges located on the frame and the disc engage to push the bronze seat faces together to achieve a tight seal. Upon opening, the wedges disengage the seat faces immediately, and the sluice gate is allowed to open free of frictional forces. Bronze is an ideal material to use for a sluice gate seat, due to its relative softness and its corrosion resistant properties. The bronze seat faces will not build up any tuberculation, even after years of remaining in the closed position
Fabricated gates typically incorporate a compressible rubber or polymer seal that is intended for more frequent usage under low head conditions. Proper design of a fabricated gate seating system relies on water pressure to deflect the disc or the seal into the frame to form a watertight seal. Designs that rely on wedging a compressible seal extremely tight against the frame will encounter operational difficulty over time.
Overall Comparison of Cast Iron and Fabricated Gates
Attribute: |
Sluice Gate |
Fabricated Slide Gate |
Composition |
Cast Iron |
Carbon Steel, Stainless Steel or Aluminum |
Type of Seat |
Bronze to Bronze |
Resilient |
Water Level |
Submerged |
Open Channel |
HFrequency of Expected Use |
Less Frequent |
More Frequent |
Application |
Submerged, High Head |
Open Channel flow control |
Mounting |
Concrete poured around cast iron thimble |
Embedded or Surface Mounted Frames |
Actuation Method |
Manual, Electric, Hydraulic |
Manual, Electric, Hydraulic |
The information in the table above is only intended as a starting point. Any application decisions should be based on a more comprehensive evaluation. Further resources and detailed product information on flow control gates are available for download from HESCO.
Follow up with HESCO regarding Flow Control Gates
HESCO is ready and happy to help you select the most appropriate Flow Control Gates for your specific application. Our partner, Rodney Hunt Company, has been the leading manufacturer in Flow Control Gates for 150 years, and together, we can provide the most knowledgeable and experienced resources, whether you have submerged or open channel flow control needs. We have assisted hundreds of engineers and operators in the proper selection, specification, and operation of both cast iron and fabricated control gates and are able to help you with your application.
There are two immediate ways that you can contact us:
1. Call Kevin Livingston or Glenn Hummel at 586-978-7200 and mention that you are following up on the ProactiView on Flow Control Gates. We will be happy to discuss with you the details of your specific application and begin to help you choose the right equipment.
2. Email Kevin Livingston or Glenn Hummel directly. Be sure to include your name, contact information, and brief description of your situation, needs and questions.
ADDITIONAL NOTE on Chlorine Feed Systems
Astute reader John Stange of the Oakland County Drain Commission contacted HESCO and shared the following observation about Liquid Sodium Hypochlorite: the ProactiView did not mention the fact that Liquid Sodium Hypochlorite (especially at high concentrations) is vulnerable to significant degradation when stored in warm temperatures. For instance, NaOCl degrades over 10 times faster at 80 degrees F than it does at 72 degrees F. In fact, if stored over the summer months in an ambient air environment, a solution of 8 percent can degrade down to 1 percent, leaving it essentially useless. So store your liquid at lower concentration and keep it cool!
In return for his excellent addition to the previous ProactiView, HESCO has awarded John Stange with a free Rodney Hunt golf shirt. HESCO will reward another reader this month that gives us the best suggestion. Did we leave something out? Do you have personal experience to share? Do you have a recommended application? Do you have a suggestion for a future topic to cover in a ProactiView? We have another fine Rodney Hunt golf shirt for the best suggestion we receive this month via email or telephone (586-978-7200) and would like to share your suggestion in the next ProactiView.