Benefits of using diaphragm pumps for hygienic applications

Benefits of using diaphragm pumps for hygienic applications 

Air Operated Double Diaphragm (AODD) pumps have been part of the industrial pumping scene for more than 50 years. These pumps are extraordinarily good “all-rounders” and boast vital performance characteristics that make them ideally suited to a wide range of hygienic pumping applications.

Applications for AODD Pumps 

AODD pumps are suitable for a host of applications, including raw materials transfer, drum emptying, recirculation, filling machines, mixing and dosing, processing and sampling. They will readily handle viscous liquids as well as fluids containing soft and hard solids such as fruit puree containing seeds and pips. This versatility makes them well suited to pumping many different fluids such as: 

 Yogurts, including various flavorings
 Creamed cottage cheese
 Cream, ice cream mix, syrups and toppings, chocolate coatings
 Margarine and fats
 Spent yeast in breweries
 Mechanically-deboned meat

The pumps have large internal clearances and flow-through which prevents clogging, with the size of solid particles that can be pumped related to the pump size. However they also have gentle pumping action which avoids damage to shear sensitive products. The pumps are capable of pumping viscous fluids since the flow rate is directly proportional to the speed of the pump. When viscous materials are pumped there are friction losses within the pump itself and between the fluid and the walls of the pipe supplying the pump. The pump automatically reduces the pumping rate as viscosity
increases and at the point where the pump can no longer move the liquid, it simply stops without damaging itself. Typically, AODD pumps can move fluids with viscosities up to 20,000 cps.

greek yogurt 2 lr
cottage cheese
bowl of ice cream
margarine
Modern winery fermenting facility.
ground meat 2
Using AODD Pumps 

Some of the key benefits offered by AODD pumps are that they are self-priming, will run dry without damage and need no electricity. Self-priming means that the pump is capable of drawing up liquid even when installed above the source liquid level and without having to have any liquid in the pump already. This self-priming characteristic means there are few restrictions on physical placement of the pump and also means that by simply attaching a hose to the inlet, the pump can be used as a “scavenger,” to completely empty containers. In addition, if the supply of fluid runs out, the pump will run dry without any damage to it. Most positive displacement and centrifugal pumps fail if they run dry, frequently because their shaft seals or stuffing boxes may require lubrication or cooling from the pumped fluid.

AODD pumps, however, simply run faster when running dry without damage. The pumps are powered entirely from compressed air, and so can be used in applications where electricity is not available or must not be used (hazardous or explosive environments). The pressure from the compressed air moves the two diaphragms inside the pump. These diaphragms form a dynamic seal that converts the pneumatic pressure on one side to a fluid pressure on the other (the fluid to be pumped). Discharge flow rates can be adjusted simply by controlling the air inlet or the discharge flow, making them extremely simple to use, with no complex control systems needed. AODD pumps are very reliable since they have very few moving parts and components that can wear. They are easily dismantled for maintenance or diaphragm replacement. These factors contribute to a low cost of ownership.

Choosing the right pump for the application 

With a wide choice of pump materials and, of course, an extensive range of sizes and pumping capacities from a large number of manufacturers, there are pumps to suit a broad range of hygienic production and transfer processes. Given this huge choice, it can be useful to consult with independent pump suppliers, who are not tied to a particular manufacturer, for advice on the most suitable pump for a given application within the allocated budget.

Meeting Hygiene Standards 
AODD pumps used in hygienic applications are manufactured from 316 grade stainless steel, with diaphragms made from sanitary grade elastomers such as Santoprene®, Buna-N, Viton® and Teflon®. The key factors which determine the suitability of a diaphragm for a particular application are: flex life, the composition of the fluids to be pumped and their effect on the diaphragm, the temperature range that the pump must operate in and the abrasive nature of the media being pumped, including the size of any particulates.
The ability to clean the pumps is also of critical importance, and pumps used in the dairy industry will generally have to conform to the requirements of at least one of the following regulatory authorities:

 FDA (Food & Drug Administration)
 3A Sanitary Standards Administrative Council in the USA
 EHEDG (European Hygienic Equipment Design Group)
 USDA (United States Department of Agriculture)

Cleaning is either carried out by dismantling the pump between batches or carrying out clean–in-place (CIP) procedures. AODD pumps contain fewer moving parts than many other types of pumps and can be easily dismantled for cleaning. Many of the materials used for manufacture will also be resistant to the chemicals used in CIP processes.

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4 Pump Mistakes You May Be Making

4 Pump Mistakes You Might Be Making 

 
In sanitary processing, pumps are one of the most critical pieces of equipment in the plant. Your company has invested the money in equipment.
Then what? How do you make sure you’re getting the most out of your investment?
Here’s a few common mistakes that companies make.

Choosing the wrong type of pump

A pump is simply defined as a device that raises, transfers, delivers, or compresses fluids or that attenuates gases
especially by suction or pressure or both. Pressure, friction and flow are three important characteristics of a pump
system. Pumps are typically classified by the way they move fluids. In sanitary processing, the most common types are
positive displacement (PD) pumps, centrifugal (or rotodynamic) pumps, diaphragm pumps and twin-screw pumps. So
which type is right for your process? That depends on several factors.


Pumps are commonly rated by horsepower, flow rate (gpm), outlet pressure (feet of head), and inlet suction (defined as
suction feet of head). The head can be simplified as the number of feet or meters the pump can raise or lower a column of
water at atmospheric pressure. From an initial design point of view, engineers often use a quantity termed the specific
speed to identify the most suitable pump type for a particular combination of flow rate and head. Therefore, to ensure
you choose the right pump for the application, the following is a list of questions you will need to answer.

Material Properties 

What is the material being pumped?
What is the material viscosity?
What is the material density or specific gravity?
What is the particle size?
What is the temperature of the material?
Is the material abrasive?

Process Conditions
What is the desired flow rate?
Where is the feed tank relative to the pump?
What is the suction lift distance?
What is the head pressure?
What is the discharge distance?
What is the inlet and outlet hose diameter?

Other Considerations
What certifications are required (FDA, 3-A, EHEDG)?
Will it be used for COP or CIP?
What is the desired price range?
What is the pressure of the shop air?
Who will clean and service the pump?
What special applications need to be considered?

Selecting the wrong size motor

There are at least three major considerations to keep in mind when sizing a motor to drive a pump:

  • What are the power demands of the pump?
  •  What will typical operation look like for this pump?
  • Will the pump be operated on a variable frequency drive (VFD)?

While you don’t want to undersize a motor, the vast majority of motors are designed with a 1.15 service factor which will
provide a bit of an insurance policy. Most motors are generally sized at predetermined intervals which means you will need to round up to the next available motor size when determining how large a motor to couple up to a pump. So if the pump power requirements indicate that the motor should be rated for at least 1.5 HP, you’ll have to round up to the next normal motor rating: 2 HP.

It’s important to size a motor properly. Doing so will produce a pumping unit that is more efficient and provides a longer
service life. Failing to size the motor correctly will result in a pumping unit that demands more power than it should or one that produces repeated electric faults and may suffer from premature motor failure.

Operating away from the Best Efficiency Point

The most common pump in sanitary processes is the centrifugal pump. When selecting a pump, an engineer will refer to a pump performance curve. The Best Efficiency Point (BEP) is a term that identifies an operating region along the pump
performance curve. It is defined at the flow at which a pump operates at the highest or optimum efficiency for a given impeller diameter.

Operating your pump too far to the left or right of the BEP can increase your operating cost and reduce the life of your pump:

  • Cavitation – caused by the formation of vapor bubbles which violently collapse, damaging impeller surfaces and reducing the
  •  time between repairs. It typically occurs when operating too far right of BEP. As the flow increases beyond the BEP, Net Positive Suction Head required (NPSHr) also increases. When this exceeds the Net Positive Suction Head available (NPSHa), cavitation occurs.
  • Vibration – when pumps operate too far right of BEP, excessive vibration can occur. Some may be caused by cavitation. It may also occur due to higher bearing loads associated with the pump operating too close to shut-off conditions. The net effect – bending and damage to the shaft.
  • Reduced bearing and seal life – Cavitation and vibration will increase your maintenance costs as seals and other internal components will wear and need to be changed more frequently. Rotor instability, shaft vibration and/or failure, and higher bearing temperatures all lead to premature breakdown of lubricants and seals.

Not performing regular maintenance

Pumps, like all equipment, need regular TLC to keep them operating at top conditions and to get the longest life from your investment. The cost of regular maintenance and repair is very small when compared to the cost of major equipment breakdowns and lost production. Depending on the amount of use, regular inspection should occur every six months. The operator should check the seals and lubrication and look for signs of wear. Most manufacturers offer pump repair options including clearance checks, replacement of rotors, bearings, shafts and other internal components.

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