Diaphragm Valve vs. Ball Valve

Sarah
DeGuzman

Irrigation, industrial process control, and household applications such as on/of valves, and laundry washers require either diaphragm or ball valves.

So how do you know which is the best to use for your application? Let’s look at the difference between the diaphragm and the ball valve.

In this article, you will learn about the function of the diaphragm valve vs. the ball valve, applications, and advantages and disadvantages of both types.

Function

The main difference between diaphragm and ball valve deals with the way that each valve controls flow.

Ball valves provide a spherical shell of metal that rotates in and out of the flow path. Ball valves are ideal for on-off control. Quarter turn actuation starts or stops flow by positioning a metallic ball in a straight-through flow path. The hollow, perforated, pivoting ball controls the flow through it. The ball valve uses a transmission to move the valve handle, which causes the ball to rotate around an axis perpendicular to the flow.

Diaphragm valves provide a flexible elastomeric diaphragm consisting of a valve body and a seat onto which the diaphragm shuts. The diaphragm valve provides rapid shutoff and precise actuation. It presses a flexible sheet pressed that narrows the flow path for fluid. Diaphragm valves provide the highest cycle life among all the valve types. 

Applications of Diaphragm Valve vs. Ball Valve

Prior to choosing a valve, the chemical composition of the system media, flow rate, temperature, and pressure must be considered. Any actuation requirements and desired shut-off response rate should also be known.  

Ball valves provide easy operation and long service life. Their production cost is low, and they can withstand high pressure, velocity, and temperature flows. The force required for valve actuation is lower than gate valves and globe valves. These characteristics make ball valves a typical process control choice in standard industrial applications.

Also, ball valves cannot be cleaned easily. This reduces their use in medical and food and beverage applications. They are also not a good choice for sustained throttling applications.

Diaphragm Valve use in pharmaceutical industry
Courtesy: iPolymer

On the other hand, diaphragm valves, find common use in corrosive and abrasive fluid applications. Their design for higher operating pressures lends to their use in industrial facilities and process applications.

For instance, power plants and chemical industries usually use diaphragm valves. Also, diaphragm valves see employ in wastewater, industrial, and municipal applications. Paper manufacturing, pulp, and other industries that deal with slurry generation and control, such as cement mining and alcohol production also use diaphragm valves frequently.

Advantages and Disadvantages

Ball Valve Advantages:

  • Superior ease of protection. Has a good sealing performance and will have no leakage.
  • Maintains and regulates high volume, high pressure, and high temp flow. Could withstand high pressure up to 400 bar even more. Also could withstand high temperature up to 350°
  • Rugged construction and long service life. Easy to repair and maintenance to extend the life span.
  • Low purchase and maintenance cost. Offering the cost-effective valve solution for projects.
  • Able to work without any side loads.
  • Allows for a seat and seal inspection and maintenance without removing the valve body from the line.
  • Does not require lubrication.

Ball Valve Disadvantages:

  • Throttling features are poor. The partially exposed seat in a throttling position may be prone to degradation due to high-velocity flows. As a result, long-term usage is not advisable.
  • Wear and tear are inevitable. When use to regulate in the wrong type of fluids, such as slurries, ball valves stuck in place. This happen when it traps the suspended particles. The valve may wear out, become damaged, or become stuck as a result of this.

Diaphragm Advantages:

  • Utilized as throttling and on-off service valves.
  • Because of the diversity of linings available, they provide good chemical resistance.
  • Stem leaking is no longer an issue.
  • Provides bubble-tight service.
  • It does not trap solids, slurries, and other contaminants in pockets. It works well with slurries and thick liquids.
  • Hazardous chemicals and radioactive fluids work well with these valves.
  • Because these valves do not allow contamination of the flow medium, they work well in food processing, pharmaceuticals, brewing, and other industries with zero tolerance for contamination.

Diaphargm Disadvantages:

  • The weir may prevent complete drainage of piping. 
  • Diaphragm valves are limited sizes, usually NPS ¹⁄₂ to 12 (DN 15 to 300).
  • Applies only to moderate pressure of approximately 300 psi.
  • Applies only to moderate temperatures of around -60 to 450 F.
  • Do not work for multi-turn operations.
  • Their body should be of corrosion-resistant material.