Nobody likes a leaky pump and the unscheduled downtime and increased maintenance needs. When these pumps are moving aggressive acids and slurries, they can leak faster and when they do leak they create an unsafe work environment.
Obviously, the biggest contributor to this problem is how quickly mechanical seals in conventional pumps wear out in these kinds of environments.
An often overlooked alternative is the Air Operated Double Diaphragm Pump (AODD). This is because AODD chemical pumps can vary in both quality and effectiveness for this application across the market. However, there are AODD pumps on the market which are ideally suited for pumping hazardous materials.
Why Use an AODD Pump?
AODD pumps use bolts to secure the pump and create their seal – so there is no mechanical seal that will need regular replacement – saving money over electric pumps. As their name suggest plastic pumps can be made of a plastic that doesn’t react with the materials you are pumping – which gives it a longer life compared to other options.
Unlike electric pumps, AODD pumps can run dry and deadhead without the risk of burning, seizing, or harming their components. Finally AODD pumps are gentler than electric pumps – with hazardous materials being fragile – mild turbulence from passing through an electric pump prevents damage to the material.
What Can Cause Leaks In AODD Pumps?
We all know that safety is the number one concern when dealing with hazardous materials. In order to use AODD pumps in your facility to move hazardous materials it’s a good idea to understand the common causes of leakage and how to remedy it.
For moving hazardous materials the most common AODD pumps used are plastic and the most common cause of leakage in a plastic pump is creep and cold flow.
Creep is when a pump deforms (permanently) under load.
Cold flow is when the pump is subjected to continuous loads at a fluctuating temperature – this can cause the different plastic parts to expand and/or contract at different rates which causes deformation of the pump.
Creep occurs over the life of any pump. It is just a more common cause of failure in plastic pumps because they don’t corrode the way metal pumps do. You can expect a good 10 years’ service out of the right AODD plastic pump for your application.
Is it time to replace your hazardous materials pumps?
If your hazardous materials pumps have a corroded pump exterior, leaks around the manifolds, worn internal fluid bowls and discoloration on the floor caused by severe leakage, it might be time to look at replacing that pump. Get in touch with the team at Pye-Barker at 404-363-6000 or drop us a line firstname.lastname@example.org and we can explore your options for replacing that pump.
In December, I shared with you 3 Air Operated Diaphragm Pump (AODD) installation traps. There are another 3 common installation traps that I see maintenance teams make when installing them.
I thought I’d share these with you here to save you the time and hassle of having to wait until something stops working on your AODD pumps to go and troubleshoot it and fix it.
AODD Pump Installation Trap #1: Prime the Pump According To Directions
A lot of plants choose to use AODD pumps when self-priming is required. If you just switch the air flow from off to the required flow rate, you may find that there is not enough time for the fluid to be drawn into the pump to prime it…
This can be avoided by just turning down the compressed air at the regulator for a few seconds – letting the pump work at the reduced pressure – which allows it to draw the fluid into the pump and prime it.
Then you can turn the pump back to full operating speed.
AODD Pump Installation Trap #2: Ensure Your Tubing and Piping Is The Correct Size
The inlet and outlet ports on your pump are selected based on the flow rate you specify. Make sure your inlet and outlet hoses match the pump’s ports.
The main reason is cavitation. Too little flow to the pump and you’ll end up with cavitation which can ruin a pump in no time flat – leading to costly downtime and repairs. Getting the pipes to match the flow rate is worth the fraction of extra investment upfront to avoid the future problems.
Also – I’d recommend using flexible inlet/outlet piping rather than hard plumbing the pump in. As the pump speed increases the vibration increases which elevates the risk of loosening hard plumbed inlets/outlets – creating a risk of leaks forming.
AODD Pump Installation Trap #3: Clear Fluid Line Restrictions During Maintenance.
Honestly, you’d be surprised how often this step gets missed. We get called in on pumps that have broken down and find all sorts of restrictions in the fluid line. We point this out to the client and they mumble something like - “The maintenance team is supposed to look after that.”
If you’ve got a problem with your maintenance team cutting corners, be sure to inspect them – find out who’s doing their job and who isn’t. Also, it’s not hard for a maintenance supervisor to listen for the tell-tale sound of gravel in the pump or flashing around the manifold elbows which indicate cavitation.
Make sure your maintenance team is checking for
Doing your maintenance is like going to the gym for most people… We hate doing it but we feel better afterwards. If you have any questions about your existing air-operated diaphragm pumps then get in touch with our team on 404-363-6000 or drop us a line email@example.com and we can get your questions answered.
We recently dealt with a customer who extrudes cottonseed oil. This customer was using diaphragm pumps when we encountered their setup. These pumps were taxing the entire system, causing a number of efficiency problems, as well as requiring frequent maintenance. In short, they were costing the company both manpower and operational hours, which adds up to a lot of money. Looking at the system, it was clear that the pumps were inadequate for their operation.
We recommended the customer upgrade to some top-of-the-line Viking spur gear pumps. While the initial investment might have been more than the previous pumps, the overall cost of ownership would be substantially less. Immediately, the customer noticed that the operational improvement. The capabilities of their system had never been higher, and they no longer needed to worry about constant repairs. The benefits are not just short-term though. Years down the line, they will have saved money on repairs and made money from being able to run their system more often and more efficiently.
When one part of your system is overworked, it spreads quickly to other components. In this case, the diaphragm pumps put undue tax on the air compressors. When you are in an industry where every second counts, the last thing you want is to be worried about when the next problem might spring up. The costs of substandard equipment are both direct and indirect, and business owners don’t need the added stress. Thanks to Viking, this company has a low-maintenance, high-performance pump, and the owner is much happier as a result.
We all love Air-operated double-diaphragm pumps (AODD) because they are easy to operate and inexpensive to repair. However there are some installation traps that will see your new AODD pump not living up to its potential.
AODD Pump Installation Trap #1: Not Installing Your Inlet Line To The Specified Size and Pressure
All too often we hear about AODD pump owners who haven’t installed the specified air line. Usually the installed line is too small (thankfully almost nobody installs a line too large).
When the line is too small, the pump doesn’t have enough power to operate at peak efficiency. And we provide pumps that will operate at peak efficiency based on your system’s requirements. So install the pump to the specifications provided…
To insure your pump gets the required air pressure, we’d recommend installing an air regulator between the compressed air supply line and your AODD pump. Too much back-pressure and you can stall the pump. Too little back-pressure and the pump won’t supply the desired flow at the desired pressure.
So if you want peak performance from your pump then you need constant pressure from your compressed air system.
AODD Pump Installation Trap #2: Failure To Inspect Sealing Surfaces for Leakage
The most common forms of leakage in an AODD pump are loss of torque over time. Over time your pump materials will stretch – this in turn can cause your sealing surfaces to loosen – creating leak paths.
Make sure you replace all your polytetrafluoroethylene (PTFE) O-rings during services. Once your PTFE O-Rings have been compressed they don’t spring back to their original shape. Which means the connection is more likely to leak. Which in turn means unnecessary downtime while you fix it.
O-Rings and maintenance technicians are a bargain compared to unscheduled downtime for critical downstream applications.
AODD Pump Installation Trap #3: Forgetting To Inspect For Muffler Icing And Restrictions.
AODD pumps are loud. This is why everyone recommends installing mufflers during installation. As the air passes from the pump to the muffler it is subject to rapid temperature changes – muffler exhaust is often below freezing – which can cause icing in humid environments.
Keep an eye out for erratic pump oration, humid inlet air or frost on the outside of the muffler – these are all signs your pump is not operating at peak efficiency.
If you have these symptoms, you can try these quick fixes:
That wraps up the first three air-operated diaphragm pump disasters. We’ll be back with part 2 soon. If you have any questions about your existing air-operated diaphragm pumps then get in touch with our team on 404-363-6000 or drop us a line firstname.lastname@example.org and we can get your questions answered.
It’s a common problem across a number of industries using Double Diaphragm Pumps to experience vibration on both the intake side and the discharge side of a pump.
These vibrations often result in damage to piping systems and the pumps themselves. Sadly in many industries vibrations and inconsistent flow are often tolerated because of an unwillingness to look for an easily found solution or because of ‘false economics.’
When clients of Pye-Barker look at the price for installing pressure dampeners to prevent vibration in a pumping system or create a desired even output, and then make any sort of comment about price – I often remind them it is really cheap.
Compared to replacing the pump or having to replace your piping system. And really cheap compared to a way to undo mounting fatigue.
Here are four common industries that can drastically reduce waste and maintenance costs as well as, increase productivity by using pulsation dampening in their pumping systems:
Chemical Companies: When pumping products such as surfactants or even volatile chemicals, these substances can aerate leading to foaming or excess vaporization (waste). This can create problems for both storage (requiring longer settling time) and for filling the final containers efficiently (causing overspray, wasted material and rejected product).
Installing the right pulsation dampening system can in many cases eliminate the problem of aeration.
Paper Production: Unloading pumps can experience vibrations and pulsation so strong that it can cause pipe stress, mounting fatigue and even rip the pump from its foundations. Which will obviously lead to unacceptably long downtimes and create a health and safety risk.
Simply installing the correct pulsation dampener on the discharge side of the pumps will reduce mounting fatigue and pipe damage.
Steel Processing: Using plunger pumps in the descaling process can result in erratic flow of the raw material which causes de-scaling to be erratic. For the best results in de-scaling, steel processors need a steady flow of raw material through the de-scaling processor.
Installing the right pulsation dampener on the discharge side of the pump as well as an inlet stabiliser will reduce the vibrations to allow uniform descaling of their raw materials. It also means the entire pumping system no longer violently vibrates. Saving on maintenance and repairs.
Waste Water Processing: When using reciprocating pumps to move waste water – many water treatment operations experience pulsation in on the discharge sides of their pumps. This can cause pipe joints to break and crack discharge pipes.
Pipe damage like this can lead to leaks and easily preventable downtime, which can be prevented with a pulsation dampener solution.
Regardless of what industry you are in and what you are pumping, if your pumping systems are experiencing vibration or water hammer which is damaging pipes, causing downtime or disrupting your operational efficiency; Pye-Barker can supply and install the pump dampening solution for your problems.
Give us a call on 404-363-6000 or drop us a line at email@example.com, we’ll take care if the rest.
A couple of months back I shared with you three all too common mistakes I see our clients’ maintenance teams make that damage their pumps and shorten their lives, leading to costly repairs, more downtime and unnecessary replacement.
So if you have budget to burn and really want to give us the money to prematurely replace your pumps then by all means do the OPPOSITE of what I’m advising you to do here.
Otherwise – if you want to minimize your downtime and maintenance costs while maximizing the life of your pump then I suggest you avoid these pump ruining ‘tricks:’
Letting Your Pump Run Dry
Don’t do it. When your pump runs dry it can quickly cause pump cavitation and mechanical seal damage – Mechanical seals can get so hot when a pump is running dry that it can shatter in about 30 seconds.
So if a pump is running dry for any reason - shut it off as soon as possible - but RIGHT NOW would be better.
Blocked Balance Holes and Vanes
When solids that are too big get pulled into the pump they can block up your balance holes and vanes. When this happens your pump is at risk of having unequal pressure which creates and an impeller imbalance.
You’ll see priming issues and high vibration. If this goes untreated you’ll eventually sustain bearing and seal damage to your pump.
Regular maintenance and proper filtration of your fluids will keep the risk of this happening to a minimum.
Using the Wrong Sized Impeller
I don’t know why this happens but I’ve seen pumps that have had the wrong sized impeller put back in them during a routine service. We provide the impeller when we install or supply our pumps, for a reason:
If you’ve replaced the specified impeller with one that is too big, the pump will begin to work harder to pump your fluids – causing premature burnout.
If the new impeller is too small then it will probably not generate the flow or head you need for your system. That sounds frustrating doesn’t it?
If you’ve got a pump that is consistently down for maintenance or not lasting like you expected it to then there may be an opportunity for improvement. You can get some help just by giving one of the team here at Pye-Barker a call at 404-363-6000 or drop us a line firstname.lastname@example.org.
One of Pye-Barker’s pump suppliers – ARO was featured on the front cover of ‘Processing’ Magazine.
United DMS (the largest silver-bearing film recycler in the United States) worked through several other unsuccessful alternatives, before using ARO’s pumps and monitoring systems to drive their fluid recovery systems.
They have been so successful in their fluid recovery process that they have been used for their bulk caustic tank and caustic day tank transfer processing areas.
You can check out the full story at http://www.processingmagazine.com/magazine/features/closed-loop-control-in-silver-recycling-2/
We have a customer who does custom chemical mixing for pesticide and herbicide manufacturers. The additives used to produce these products come in both powder and liquid form. Usually the ingredients are mixed with water in large mixing tanks. The product is then moved to a smaller tank that is used as a day tank in filling the customer’s containers. They are usually one gallon and five gallon plastic bottles.
The particular product that was causing problems being mixed had a component that was very light and fluffy. They had tried different methods of moving the ingredient to the mix tank but had problems with dusting and the product would actually foam or bubble out of the top of the mix tank. This was especially true with gravity feed.
The project engineer at the facility relayed these problems to me and I suggested that they try an ARO AOD powder pump. These pumps use regulated aeration ports to keep the product fluidized. The pump also had the optional suction probe which is perfect for moving product from super sacks.
ARO offered a test program for these to insure that the pump will move the product. Our customer found that the material was easily pumped once the proper pump adjustments were made. Since the pump discharge is into a hose it was easy for them to pipe it into the top of the tank. This eliminated their dusting problem and the foaming problem with the gravity fill.
We did these trials several months ago and I recently checked with the customer and they are very happy with the pump.
Many of my customers in north Georgia who produce coatings, printing inks and light weight chemicals and typically use air operated diaphragm pumps are always asking me what we can offer for metering, dosing or being able to remote operate their dispensing operations.
Most of these customers also use positive displacement gear pumps and after learning the initial purchase prices of a variable speed positive displacement with their limited capital budgets are looking for options.
IR ARO recently launched their new Electronic Interface EXP air operated diaphragm pumps that have solenoid control rather than an air valve assembly.
The electronic interface pumps can also be supplied with optional cycle counter to track end of stroke feedback and pump data. The PE electronic interface pumps allow maximum flow rates with minimum air consumption (on average 3%+ less). The PE pumps also have lube free design with fewer parts than the standard pump with the exclusion of the air valve assembly with inclusion of solenoid valve control.
Many of my customers have several AOD pumps in operation for their dispensing requirements that historically needs intensive manpower to operate equipment, and now ARO offers a multi-pump controller that communicates with the new ARO electronic interface pumps which eliminates intensive operating with remote operation and also provides safer control.
Let us schedule a survey of your existing pumps and how they are operated, pending metering or dosing requirements, and discuss how these new improved ARO pump controls can help.
The pump manufacturer will state the NPSHr, Net Positive Suction Head required, to prevent cavitation or vaporization of the liquid in the pump. The NPSHa, Net Positive Suction Head available, must be greater than that required by the pump.
For a basic understanding of Net Positive Suction Head, you must think in terms of absolute pressure in feet. To determine the NPSHa, the Net Positive Suction Head available at the pump inlet, you first determine the pressure above the liquid. As atmospheric pressure varies with altitude (and weather), the site elevation must be known. For this discussion, we will be at sea level and pumping water.
At zero feet elevation, sea level, the atmospheric pressure is 33.9’ absolute (or 14.7psia). When you are pumping from a tank that is open to atmosphere, you automatically have 33.9’ absolute pressure helping you get liquid to the pump suction.
We will assume our tank has 10 feet of cold water level above the pump. We have a total of 43.9’ of pressure available above the pump (33.9’ atmos. pressure + 10’ liquid level).
That 33.9’ of atmospheric pressure is reduced first by the vapor pressure of the liquid (vapor pressure is the tendency for the liquid to become a vapor).
Using water as a common reference. At 33°F., the vapor pressure of water is basically zero. As the water temperature increases, so does its vapor pressure. At 212°F, the vapor pressure equals 33.9’, the point at which water turns to a vapor.
If we heat our water tank example to 212°F, the atmospheric pressure of 33.9’ minus the vapor pressure of 33.9’ leaves us with only the 10’ of liquid level to supply the pump.
The last part of the equation is deducting the friction loss of the suction piping. This calculation will vary from application to application.
Net Positive Suction Head Available = pressure above the liquid + liquid level above the pump (negative if level is below the pump) – the vapor pressure of liquid at pumping temperature – the friction loss of the suction piping.
Although NPSH calculations are not exact, they but must be considered for proper pump selection.