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Bladder Pumps, Controllers, Methods and Mumbo Jumbo.

Bladder Pump History
Bladder pumps are the simplest form of a pump.  Looking through Google Timeline for the bladder pumps invention, I find an interesting link pointing to The Brisbane Courier Saturday 20 June 1868 as the first reference to something similar to that of a bladder pump.  A philosophical understanding that this could be used as a pump!

It’s unusual that no documentation found in my search proved it was other than this Australian Lecturer of Pneumatic “Philosophy”.  Mr Boyd’s full moon meetings, (as it seems to beat boredom) in Oxley touch on the mechanisms of what we call a bladder pump. Obviously the bladder pump must have been used in some form prior to this as a bellows pump, just in different format.

During the 1970’s and 80’s in the United States bladder pumps became associated with hazardous sampling due to the pneumatic or inert gas used to power the pumps.  It proved successful sampling in intrinsically safe atmospheres and was widely accepted by most manufacturing companies with these atmospheres as approved equipment. 

What is a bladder Pump?
If we look at parts, its 2 valves a body and a bladder.  4 parts pretty much covers the majority of bladder pumps.  Generally materials are composed of PVC, stainless steel, Teflon and other plastics. Bladder Pump Guts

 

You could describe the operation as two hemispheres separated by a flexible membrane.  One hemisphere fills with liquid by the way of a check valve, the other fills with air with the help of the controller.  The air is cycled back and forth to inflate the membrane (bladder) and displace the volume of liquid in the other hemisphere.  The three moving parts are the bladder which inflates, and an inlet and outlet liquid check valve.  No rocket science or voodoo involved.

The Controller makes its' function like ground control right?  It's true function is to control the air power to the pump.  Some use digital, some dials, but it is only controlling a vent (pump fill) and pressurize (pump discharge) cycle.  The only thing that might conflict between brands are connector and hose sizes.  There is no detriment interchanging makes.  Do you really need to spend more?

Methodology
As far as I can remember methodology tends to come from government research or university staff, In our field its driven by government agencies.

EPA Low Stress Sampling

ASTM Standard Practice for Low-Flow Purging and Sampling

Some manufacturers’ methods are being used to address a simplification of the approved methodology.  This is an alternative method and needs to be submitted for approval prior to use.  For example, QED Micropurge Methodology is a manufactures methodology not an approved standard procedure. “Low Flow Sampling” is the correct term to use.

Why did this develop into a method?

Refineries, Chemical, and Waste industries are a limited market.  Honestly the traditional market of the bladder pump sales volumes are low.  These types of industries had to use them.  As with any good ideas or products you look to diversify your market.  At the same time in a effort to reduce the volume of liquid and time need to sample USGS and Geotech developed a well bladder pump.  

Are they a good pump and method?
The logic is sound, however I see errors in displacement of volumes and lowering a pump through the stagnate layer in portable applications.  In dedicated uses like landfill the saving is tremendous over a 10 year life span.  Most live beyond that.

Method wise, I think the south pacific market has too much staff turn over to allow repeatable sampling using this methodology.  You have a lot of equipment which has to work together to provide a good sample.  Equipment in this case could be seen as a liability.  If you drive an hour and your compressor blows, water in the controller, or batteries are dead you’ve wasted time and money.  Your staff have to understand the principle of drawdown, pneumatics, hydraulics, decontamination, and building and rebuilding pumps.  There are better methods.

Bladder Pumps do Work!
I’d say it’s a case by case basis. Longevity outcome and interest as well as site all prove key in determining whether bladder pumps and Low Flow Sampling will work for you.  The traditional three volumes should go.  It’s a mindless effort at sampling however I believe more repeatable than portable low flow.

What’s next?
If the logic is sound with low flow sampling and the conduit of water flowing from least resistance.  This true proves that water flows through the screen zone of your well.  This being the case or logic, passive or no purge methods will work.

Our fastest ground form of groundwater sampler is the HydroSleeve.  Hydrosleeve’s don’t disturb the water column and a 50mm sampler displaces 60mL.  We had to give them away to start, but they have all but replaced bailers.  I’d always recommend using methods with less steps and equipment over methodically burdened procedures.

Train your staff for low flow or to pull a rope twice? Which would be more repeatable with less downtime training?

Regulators that don’t believe it!
We’re beyond give the samplers to consultants but if you’re a regulator in Australia or New Zealand let us know you want a comparison pack.  We’ll supply you a HydroSleeve for 50mm bore and weight.  We suggest either deploying them a day or more before sampling, or after your last traditional sample.  When you return collect the Hydrosleeve first, then do your traditional method after. 

The authors point of view is expressed
I am biased against the low flow method as I explain above. As a point for you to dwell, I am a scientist and a salesman, why am I trying to talk you out of spending thousands for a method that’s less than 100? It cannot be money! It’s the scientist talking.

Envco staff has over a decade of low flow and groundwater sampling experience.  We’ve used our equipment as technicians and consultants before we started selling them.  We’ve installed hundreds of pumps for our clients and we guarantee them all no matter the brand!