Bottom Outlet Valve Options for Glass-Lined Vessels

moz-screenshot-128As defined on, a valve is “a device that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways”.  This simple definition helps to demonstrate that valves are fundamental components to virtually all processes in domestic life as well as the industrial sector.  From a basic appliance to a complex matrix of systems and components, valves provide the essential capability to manage the quantity, direction, and speed of material flow. 

Bottom outlet valves, often referred to as “flush valves” or “discharge valves”, are the type we’ll focus on in this post as they are a necessity for accomplishing drainage in all glass-lined steel vessels.  Even in this niche there is a diverse selection of valve designs to choose from, all with distinctive features that make them advantageous in specific applications. 


Bottom Outlet Valve Basics

Bottom outlet valves are installed on tanks, reactors, or pipelines and are used for draining the contents from these vessels.  This type of valve is positioned at the lowest point of the vessel or pipeline to enable dead space free self-draining so that they can achieve full (or near complete) product discharge.  They are widely used in the pharmaceutical, fine chemical, petrochemical, biochemical and mineral refining industries.  Due to the corrosive and hazardous nature of many of the products manufactured by these industries, carbon steel, stainless steel, and PTFE are common materials of construction.  Additionally glass or glass-lined valves are used when GMP compliancy and CIP are required.  These valves can usually house a temperature sensor, allowing accurate and reliable temperature measurement at the lowest point in the vessel.  Manual and actuated models are available; due to the location of the valve, low-profile designs are also offered to accommodate space restrictions. 

To ensure full product flow, it’s a good idea to make sure the valve design features proportional outlet diameters.  It’s also important that the design you select minimizes dead space that could otherwise lead to product entrapment.  The stem, head, and seat design should assure a tight shutoff to avoid any material leakage.  PTFE chevron packing rings usually come equipped with the valve to further prevent leakage under pressure or vacuum (a great design that replaces the obsolete, difficult to clean bellows seal that was formerly an industry standard).  While the cleaning procedures for these valves are typically designed to be relatively simple, there is still some level of disassembly is required which can cause a delay in productivity so you’ll want to find out what the cleaning process and maintenance entails. 


Glass-Lined Valves

If the material coming out of your reactor has sticky characteristics, contains crystals or slurries, is caustic, or if cleanliness is of importance due to your industry requirements, then a glass-lined bottom outlet valve would be your desired material of construction.  With the valve being fabricated identically to the vessel itself, you can ensure no metal contamination of the process fluid.  The glass-lined design also enables use across a wide temperature and pressure range.  The wetted parts feature the same characteristics of all other glass-lined equipment including resistance to corrosion, thermal and mechanical shock.  All other parts in contact with the process are made of fluoropolymer (PTFE, PFA).


Clean Valve

The Clean Valve is a glass-lined bottom flush valve made by DDPS that is specially designed to avoid complex maintenance.   This easy-to-operate, easy-to-clean, self-draining valve allows for a variety of functions without the need to interrupt the process and without dismantling the valve.  The Clean Valve is suitable for use in virtually any process where batch-to-batch cleanability is important (it was designed with the most rigorous operations in mind).  So what exactly sets the Clean Valve apart from other “standard” glass-lined BOVs?  Here are a few noteworthy features:

  • A unique lip seal valve seat design prevents material getting between the seat and the bottom outlet nozzle
  • An additional side nozzle with a 5° downward sloping is included for a cleaning lance or other purposes (e.g. sampling, gas dispersion)
  • The glass-lined head and stem contains a temperature sensor can be replaced without having to remove the valve from service

DDPS specializes in providing bottom outlet valves to complement our range of glass and glass-lined reactors and tanks.  Our Clean Valve is unique from other bottom outlet valves and can be considered quite cost effective when considering the downtime that is avoided from not having to dismantle the valve for cleaning between batches.  The Clean Valve along with applicable spare parts is available from stock in a variety of sizes and types (manual or pneumatic).  To see the Clean Valve in operation and learn about the other enhancements available for glass-lined reactors, watch our animation “Optimizing the Glass-Lined Reactor" or read Optimizing the Glass-Lined Reactor eBook.




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