Water maker again

[sailaboutvic]

Am I just wasting my time and money using an presser washer pump for the water maker I am building ?
I have spoken to two guys who have done this , one moored three boats away ,
He had no problem in six years or so he says , the other one is only a year old .
As anyone else used an HPW pump ?
It seen the general consensus it to use a cat pump , the different is £150<> against and cat pump and motor £1200 adding the VAT .
Plus an HPW pump can be used of an inverter if every the generator packs up , more compacted and comes complete with motor .

 

[duncan99210]

I've heard of a pressure washer pump being used for a watermaker and it makes sense to me. Most of them put out enough pressure to operate the system and it'll be a simple matter to fit them as they come with an integrated motor. However, the one thing I'd check is the through put of the pump: little point in fitting a high pressure pump that won't put enough water through the system to produce a decent output. A neighbour of ours in Messolonghi a few years back with a home built system said he moved from an electric pump to a motor driven pump because he couldn't achieve the throughput he required to produce a decent flow of product water. All pumps are not equal and if you can live with a smaller throughput then the washer pump may be OK.

 

[geem]

You need something like 13 litres/min at 1200 psi. This would typically need 1.5kw motor

 

[sailaboutvic]

You need something like 13 litres/min at 1200 psi. This would typically need 1.5kw motor

Water makers like to be worked and we not looking for great amount , if we use it each day for an hour if we can get 30lts after a flash I be happy , we don't use 30 lts days so it a matter of keeping the tanks topped up .
13 lts PM flow , I think would be on the hight side for what I looking for .
480 lts hour with one membrane should give me what I want .

 

[Barbican]

My concern would be the duty cycle/life cycle of a low cost HPW pump, my HPW lasted a few years, but not many actual hours used when I think about it. I replaced it with an HD series Karcher that was much more expensive, but is still going fine, it has an oil reservoir for the pump and is rated for continuous use. My Desalator DC watermaker uses a CAT pump 247 or 277 I think, which also has an oil resevoir, and is rated at around 13l/m at 1200PSI (As Geem says). This produces up to 60l/hr but normally around 40 with water temp at its usual UK solent/channel levels.

Good luck with the project

 

[geem]

My concern would be the duty cycle/life cycle of a low cost HPW pump, my HPW lasted a few years, but not many actual hours used when I think about it. I replaced it with an HD series Karcher that was much more expensive, but is still going fine, it has an oil reservoir for the pump and is rated for continuous use. My Desalator DC watermaker uses a CAT pump 247 or 277 I think, which also has an oil resevoir, and is rated at around 13l/m at 1200PSI (As Geem says). This produces up to 60l/hr but normally around 40 with water temp at its usual UK solent/channel levels.

Good luck with the project

My Cat 247 uses a 40 inch and a 21 inch pressure vessel. We get up to 133 litres per hour but we are in the Caribbean where the sea temp is higher. We run it about every three days for about 45 mins to an hour.

 

[sailaboutvic]

My Cat 247 uses a 40 inch and a 21 inch pressure vessel. We get up to 133 litres per hour but we are in the Caribbean where the sea temp is higher. We run it about every three days for about 45 mins to an hour.

Do you just flush it out each time with fresh water ?

 

[geem]

Do you just flush it out each time with fresh water ?

I take the pre filters out and rinse about 5-8 litres across the membranes so they dont have salt water on them. If you dont do this then you get dead plankton and stuff on the membranes. I just throw the prefilters over the side on a long line so they get rinsed in sea water

 

[pcatterall]

Hope we get a write up on completion Vic?
We are interested in some sort of low volume water maker but the DIY route seems to be the only way we can afford one!
If the pressure washer seems feasible and someone nearby has used one with demonstrated success then why not go down that route?

 

[Barbican]

We get up to 133 litres per hour but we are in the Caribbean where the sea temp is higher.

Haha - sheer luxury!

 

[geem]

Hope we get a write up on completion Vic?
We are interested in some sort of low volume water maker but the DIY route seems to be the only way we can afford one!
If the pressure washer seems feasible and someone nearby has used one with demonstrated success then why not go down that route?

I dont think there is anything wrong with going the pressure washer pump route. After all that is what the Cat pump is anyway. The only difference with the watermaker specific pumps is they are made of materials resistant to salt water. Either bronze or s/s. If you installed a pair of 40" membranes and a pressure washer pump you could make enough fresh water to be able to thoroughly flush the salt out of the high pressure pump each time you used it. I dont see why this wouldnt work. I would still look for circa13 litres/min and 1200 psi rating though

 

[Barbican]

I dont think there is anything wrong with going the pressure washer pump route. After all that is what the Cat pump is anyway. The only difference with the watermaker specific pumps is they are made of materials resistant to salt water. Either bronze or s/s. If you installed a pair of 40" membranes and a pressure washer pump you could make enough fresh water to be able to thoroughly flush the salt out of the high pressure pump each time you used it. I dont see why this wouldnt work. I would still look for circa13 litres/min and 1200 psi rating though

+1 - A pump of that calibre will be fine, my desolator also does an optional automatic flush when you turn it off.

 

[JumbleDuck]

You need something like 13 litres/min at 1200 psi. This would typically need 1.5kw motor

A wee bit more, I think. Power = volumetric flow rate x pressure difference = 2.2 x 10^-4 m³ s^-1 x 8.3 x 10⁶ Pa = 1800W, so allowing for some inefficiency 2kW looks like a minimum.

 

[geem]

A wee bit more, I think. Power = volumetric flow rate x pressure difference = 2.2 x 10^-4 m³ s^-1 x 8.3 x 10⁶ Pa = 1800W, so allowing for some inefficiency 2kW looks like a minimum.

The figures I quoted are for my installation. I run a CAT 247 pump at 1450rpm direct drive from a 1.5kw motor. The figures I quoted earlier were straight from the CAT manual for the pump. They rate it at 13.6l/min at 1200 psi but at 1750 rpm. In reality we only use it at 1450 rpm and 800 psi. Not sure what the actual flow rate is but I know this pump and motor combination will drive three 40 inch membranes and give up to 200 litres per hour

 

[crisjones]

A wee bit more, I think. Power = volumetric flow rate x pressure difference = 2.2 x 10^-4 m³ s^-1 x 8.3 x 10⁶ Pa = 1800W, so allowing for some inefficiency 2kW looks like a minimum.

Watermaker membranes usually operate at around 800psi so the power requirement is only about 75% of your calculated figure. We have a Cat 247 pump driven directly by a 1.5kW motor, connected to two 40" membranes. This combination produces 120 to 140 ltrs/hr of fresh water depending on water temperature, has worked perfectly for over 5 years and the electric motor is a basic cheap motor from Machine Mart, currently about £140 for the motor. It has needed a new capacitor in that time but otherwise I can see no reason for spending more money on anything more robust, after all most pressure washers will use the cheapest motor they can find and they seem to last pretty well.

 

[crisjones]

A wee bit more, I think. Power = volumetric flow rate x pressure difference = 2.2 x 10^-4 m³ s^-1 x 8.3 x 10⁶ Pa = 1800W, so allowing for some inefficiency 2kW looks like a minimum.

Watermaker membranes usually operate at around 800psi so the power requirement is only about 75% of your calculated figure. We have a Cat 247 pump driven directly by a 1.5kW motor, connected to two 40" membranes. This combination produces 120 to 140 ltrs/hr of fresh water depending on water temperature, has worked perfectly for over 5 years and the electric motor is a basic cheap motor from Machine Mart, currently about £140 for the motor. It has needed a new capacitor in that time but otherwise I can see no reason for spending more money on anything more robust, after all most pressure washers will use the cheapest motor they can find and they seem to last pretty well.

 

[sailaboutvic]

A cat 247 277 pump are what most people use with a DD onto an 1.5 HP motor , I have one good friend who putting one to gather as we speak ( thanks Albert if you reading this for the info you sent me and Chris ) .
My concern is I would need to run my 4kv gen , ok while it's working but if it ever stop that also mean no water maker ,
Anther thing to think about is the gen uses about 1 lts of fuel an hour , if we use it every day for water that's going to be expensive water .
With an power wash pump , we could run it on an inverter while we using the engine .
I agree an power wash pump not going to last long but @ the rate of a Cat pump , bell housing and motor , I could but 10 Power wash pump compair to one Cat .
Look at it another way if a PW pump last a season it will be 10 year before it cost me the same as a Cat pump and by then the Cat pump might be on it's last legs .
Plus with a power washer you will get most of the fitting and pipe work.
On the other hand if the PW pump is only going to last a few months , well then is not worth the trouble of keep replacing it.
Hence this posting here ,

 

[Heckler]

Am I just wasting my time and money using an presser washer pump for the water maker I am building ?
I have spoken to two guys who have done this , one moored three boats away ,
He had no problem in six years or so he says , the other one is only a year old .
As anyone else used an HPW pump ?
It seen the general consensus it to use a cat pump , the different is £150<> against and cat pump and motor £1200 adding the VAT .
Plus an HPW pump can be used of an inverter if every the generator packs up , more compacted and comes complete with motor .

Have had a KEW pressure washer for 30 years, semi pro for a business I had. It sprang a lek and the hose went, no parts! So i bought a new fangled one. Curiosity got me, I took off the pale blue plastic cover and found a rotted pressure guage which I removed and blanked off, the rest of it is bronze and very substantial, I suspect it will make a good hi pressure pump for a water maker

 

[Heckler]

Hope we get a write up on completion Vic?
We are interested in some sort of low volume water maker but the DIY route seems to be the only way we can afford one!
If the pressure washer seems feasible and someone nearby has used one with demonstrated success then why not go down that route?

Peter
if you are in the Uk you are welcome to my KEW pump, trip to Llangollen next week?
Stu

 

[sailaboutvic]

Watermaker membranes usually operate at around 800psi so the power requirement is only about 75% of your calculated figure. We have a Cat 247 pump driven directly by a 1.5kW motor, connected to two 40" membranes. This combination produces 120 to 140 ltrs/hr of fresh water depending on water temperature, has worked perfectly for over 5 years and the electric motor is a basic cheap motor from Machine Mart, currently about £140 for the motor. It has needed a new capacitor in that time but otherwise I can see no reason for spending more money on anything more robust, after all most pressure washers will use the cheapest motor they can find and they seem to last pretty well.

Hi Chris
247 Cat with the bell house to fit an DD motor is just over £800 plus VAT then there carriages so I guess it's be around £1000 pounds so if the worst come to the worst I have to take that route .
Manage to get vessel and membranes 2.5 x 40 £400 , slowly the parts are coming to gather .
Might get it finish by the end of this winter with some luck .
Just the pump has got me puzzles for now .