I don't think it is a good idea to use a diaphragm pump for lime slurry, first because you can't be sure of the quality of the chemical solution and second because it will likely damage the pump and lead to blockage of the check valves.
I would suggest your go for a progressive cavity pump with safety features such as dry run protection.
I manufacture lime slurry. I would never recommend anything but a hose pump to feed lime slurry. Our concentrations are 30-35%. If you use a diaphragm pump you will have to dilute your lime to a 15-20% solution just to be able to feed it. With the hose pumps you can run your product straight and maybe have to replace the hose once or twice a year.
We use seepex positive displacement pumps and the stator wears out every 12-18 months or so. Of course, our pumps only for for about 10-20 minutes every hour.
We also use some gorman-rupp trash pumps to recirculate our holding tanks.
I would not recommend diaphragm pumps for similar reasons as others have stated. the lime will clog the pump and all of its parts. we replaces hoses on our system every couple of months and flush our lines out on every run. lime slurry builds up inside the piping system, and will the same in your diaphragm pumps.Good luck! Remember, the chisel and hammer is your friend. :)
I used a single diaphragm direct drive pump for years with lime slurry sourced from acetylene manufacture and never had a problem.
That being said, the system was in place before I got there, and I never had to replace it in my 8 years there. We replaced the diaphragm twice and the packing glands annually. It was a piece of equipment that was almost 'fire and forget.'
I wish that I could remember the brand...
That being said, I wouldn't use an air driven double diaphragm pump on it. I used the heck out them on non-mission critical chemical sludge transfer.
It is actually possible to use diaphragm pumps for lime slurry metering. But you need to know which ones.
I've used them for many years with slurry of 50 to 80 g/l. It takes a stainless steel hydraulic pump with stainless steel valves. NB: you need to rinse out the pump and the valves with each stop. I was using pumps with a flow rate of between 200 and 500 l/h. It may not work as well on smaller flows, as the valve size is more susceptible to clogging.
But the current trend is towards peristaltic pumps, which, in my opinion, are more effective. I would avoid progressive cavity pumps as their rotors are quickly worn down by the impurities in the slurry.
I would really avoid the diaphragm pump with lime slurry.
I second the recommendation, however, for peristaltic pumps, which can turn more slowly to prevent wear on the stator. There are several suppliers of this type of equipment.