How to select the correct Husky pump

Air-operated double diaphragm pumps are the preferred pumps in many industries as they perform well in a broad array of applications.

Graco Husky AODD pumps can handle a wide range of chemicals, flow rates and viscosities. But how do you choose the best pump for your specific application? Here are a few guidelines to help.

Graco’s Air-Operated Double Diaphragm (AODD) Husky pumps are available in metal and plastic housings, take balls, seats and diaphragms of various materials, and offer a wide range of flow rates and sizes. To select the right Husky pump for your specific application, a few questions need to be answered. 

What fluid will it be pumping? Every fluid has its own characteristics. Pumping water requires a different approach to pumping glue, an epoxy, tomato paste or an acid. Understanding the characteristics of the fluid is the first step towards choosing a suitable pump.

What’s the application? Are you feeding a pump or another machine? Are you transferring fluid, unloading a tank, or is it a potting or some other application? 

What’s the diameter of the pipes? A double diaphragm pump delivers a lot of volume but at low pressure, so pipe diameter needs to be as high as possible. How much volume do you need for your application?

Where will the pump be positioned? Are you creating suction height? What length of suction hoses are you intending to use? Discharge length is a big factor; the longer the discharge length, the more pressure losses you will experience.

Intermittent or continuous operation? If your pump will be running 24/7, you may need to go to a lower cycle rate, which means a larger pump size and thus a higher price. However, a lower cycle rate results in less wear of the packings, diaphragms, seats, and balls, resulting in reduced maintenance costs. 

Do you need ATEX certification? If the pump is going to operate in a hazardous environment you may need to choose a pump with ATEX approval. ATEX certification ensures that equipment will work safely in an explosive environment without causing an accident, if used as per the manufacturer's recommendations.
 

A typical sulfuric acid pumping application

Going into more detail on the application: you want to pump sulfuric acid at 20oC from a 1200-liter tank to feed a conditioning unit that over the course of a day will fill 5-liter barrels at a speed of 30 liters per minute. The feed tank is 3 meters high and then there is 1 meter of horizontal pipe followed by a 5-meter discharge pipe. 

At a speed of 30 liters per minute, your pump will have a duty cycle of only 40 minutes, so it’s operating intermittently. By using the Graco Suction Loss Calculation Sheet you will discover that the estimated suction losses for such a setup are 0.59 bar. This leaves 0.41 bar remaining, which should be sufficient. 

We advise that with high suction heights and heavy fluids such as sulfuric acid it’s worth putting an exit check valve at the bottom of the 1200-liter barrel. This will ensure that the wet suction is always higher than the dry suction. Another recommendation is to lower your pump if possible. This not only ensures you make the most of gravity, but also allows for perfect priming of the pump. 

Selecting the right balls

With a high-density fluid such as sulfuric acid, a heavier ball will be needed, such as one made from Viton® or PTFE. Viton® is more expensive than PTFE, but as it is more dense and therefore heavier it will give a better suction. This is a key consideration for the sulfuric acid application with its 3-meter suction height. Santoprene® would not be a good option for this application as Santoprene is lighter than water. Balls made from Santoprene® will float on most fluids.
 

Overview of Husky pumps for the sulfuric acid application

For a low cost, no ATEX solution:

• Husky 1050 polypropylene body + Santoprene®/Viton® inner parts
• Husky 1590 polypropylene body + Santoprene®/Viton® inner parts

For a low cost pump with ATEX approval:

• Husky 1050 conductive polypropylene body + Santoprene®/Viton® inner parts

For a high temperature pump, no ATEX approval: 

• Husky 1050 PVDF body + PTFE inner parts
• Husky 1590 PVDF body + PTFE inner parts 

For a high temperature pump with ATEX approval:

• Husky 1050 Hastelloy® body + polypropylene center section + PTFE inner parts

For a low cost chemical pump with no ATEX approval:

• Husky 15120 polypropylene center section + Santoprene® inner parts
• ChemSafe 1040 full PTFE body + PTFE diaphragm 
• ChemSafe 1040 full polypropylene body + PTFE diaphragm
   

How much air do these pumps consume?

A double diaphragm pump consumes a lot of air. So don’t forget to add the cost of an air compressor into your calculations. Typically, a pump running continuously could easily consume 750-850 liters per minute. However, in practice this is very unlikely as these pumps usually run intermittently. Your air compressor supplier will be able to advise on the best air compressor to use for your specific application. 
 

Need help choosing your pump?

Graco offers some helpful tools on its website. The Chemical Compatibility Guide is an excellent general guideline for pump selection and to determine compatible materials, not only for the fluid being pumped but also for the cleaning agent to be used. Another useful guide is the Materials of Construction Guide which allows you to find the most cost-effective match for your application. And last but not least, the Pneumatic Diaphragm Pump Selector will help you select the right pump for your specific application. 

If you require further assistance, or would like to see a demonstration of a Husky AODD pump, please fill in the contact form below. 

Santoprene® is a registered trademark of Advanced Elastomer Systems, L.P. Hastelloy® is a registered trademark of Haynes International, Inc. Viton® is a registered trademark of The Chemours Company. Kynar® is a registered trademark of Arkema Inc. Hytrel® is a registered trademark of DuPont.