Next message: Giff Hammar: "RE: lv-ab: cabin heaters"
In a message dated 10/09/2004 04:08:51 GMT Daylight Time,
writes:
> In a message dated 9/7/2004 10:18:45 AM Eastern Daylight Time,
> writes:
>
> >> Norm:
>> Now that you've had it for a while, what are your impressions of the
>> Spectra
>> water maker? Do you like it? Does it produce anywhere near the rated
>> capacity? Just wondering . . .
>> Chip Wilson
>> s/y 'Ajax'
>> Fort Myers Beach, FL
>
> Spectra is very proud of their gear so I bought only the low pressure pump,
> the high pressure Clarke Pump and the pulsation damper from a Spectra dealer
> in New York. I got the membrane and housing from SK Watermakers, the
> prefilter housings from Home Depot, the prefilters from Farm Tek Supply, stainless
> gauges from a local auto supply and a high powered low pressure pump from
> Depco in St Pete FL.
>
> The membrane and housing are a standard 40" type. These membranes are
> standard, common, and available from any RO dealer. This keeps the price down.
> This is the opposite from my Village Marine Tech unit that takes an odd size
> membrane available only from Village Marine Tech at "you pay our price or
> throw away your watermaker" prices.
>
> The high pressure "Clarke Pump" is unique. It is actually a pressure
> booster that takes the low pressure water at around 100 psi and boosts it to
> several hundred psi for the membranes. I have had no problems with it yet but
> seawater dribbling from its control valve is corroding the base plate, a job on
> list #2.
>
> I hooked up both small and large low pressure pumps in parallel. The
> circuit was: sea valve, sea strainer, both low pressure pumps in parallel, 20
> micron filter, 5 micron filter, pulsation damper, Clarke Pump, membrane, overboard
> sea valve. There are some valves and gauges also.
>
> I could choose which low pressure pump to be used with switches. They both
> had check valves on their outputs.
>
> At first the system performed as advertised, but within a few days the
> output fell rapidly to less than 5 gph.
>
> The small low pressure pump, which came with the Clarke Pump, failed early
> on. First the high pressure limit switch failed so I bypassed it. Then it
> started leaking, so I removed it. Then the pump output fell to unusable
> levels. The dealer I got it from in NY refused to sell me any parts and told me
> (apparently I was talking to the "boss") that he would not have sold me the
> gear in the first place. He did not say why and I did not ask but my guess is
> that he would realize a much greater profit if he had sold me a complete
> system. I have not used that pump since.
>
> The large low pressure pump I bought from Depco after carefully examining
> the one offered by Spectra and I believe I have substantially the same pump for
> $250 less than Spectra's price. This pump is an Italian rotary vane type
> pump with graphite interior and built-in relief valve. Both pumps have 12 VDC
> motors. It worked well at first producing 18 gph, but it too gradually failed
> until I was getting less than 5 gph of product.
>
> After examining the entire situation I concluded that the high silt level of
> seawater in St Augustine was the culprit that destroyed both pumps by
> abrasion.
>
> The Depco pump was sent to Depco for rebuild, thence to the distributor in
> CT and they replaced the interior parts "gratis". They agreed that the
> abrasion of the silt probably killed the pump. However, only the soft interior
> parts needed replacement and they were relatively inexpensive. I could order
> the parts and replace them easily myself.
>
> When I got the pump back I rebuilt the system but this time with the two
> filters upstream of the Depco pump to protect it from silt. I had to add yet
> another pump upstream of the filters, between the sea strainer and the filters,
> to push the water through the filters to feed the Depco pump. This is a
> Flo-Jet type general purpose pump.
>
> This setup works well now, putting out 14 gph of product.
>
> But I am in the relatively clean water of New England and do not know how it
> will stand up to the heavy silt of St Augustine.
>
> As things stand now, this system is not safe for unattended operation
> because there is no auto shutdown for the system if the feed water pressure to the
> Depco pump should fall below zero due to fouling of the filters and cause
> cavitation of the Depco pump. Cavitation of this pump is not a Good Thing and I
> would need to rig some sort of auto shut down. When I am on board now, I
> can hear it complain and shut it down. I also would like another gauge showing
> the Clarke Pump's feed water pressure and maybe the RO membrane feed water
> pressure.
>
>
> I would also like to rig (I have all the parts, just haven't had the
> time...) a diverter valve and timer to dump the first three minutes of product (it
> is salty at first) so that, with the anti cavitation shutdown system, the rig
> is capable of fully automatic operation. I could then hook it to the Trace
> inverter, which has three programmable voltage (12 VDC) sensitive relays I
> could set to turn on the RO when the batteries are fully charged by the solar
> panels and wind generators.
>
> So far the system works, producing 14 gph of good fresh water but at a cost
> of 30 amps.
>
> Perhaps with more reengineering I could get the efficiency up. Spectra
> claims one amp hour per gallon, and this is probably possible with a small low
> pressure pump in clean seawater in the original configuration. But like many
> advertised specs, it has not worked out this way in the real world for me.
>
>
> Norm
> S/V Bandersnatch
> Lying Gloucester MA
>
Spectra gear is good but contains some CRAP engineering - the fittings onto
the Clark pump and the membrane end cap have a tapered thread to seal them on
the early versions - later versions have a straight thread and an O-ring seal -
then the hole on the end cap of the membrane is off centre and near the edge
- seen and experienced cracks on both the clark pump and the membrane end
caps. Yes, the clark pump has a lifetime warrantee BUT Spectra expect you to
place a $18K deposit before they will send you a new one After much shouting a
squealing the Spectra dealer in St John US VI's 'Proper Yachts' got our cracked
pump replaced but he had to lodge the deposit mmmmmmmm!!!! In the VI's 1 AMP
per gallon is achievable with some care 'sea grass blocking the inlet being the
big concern' the twin pump option would be great. Do give me the info on
this 'alternative' cheaper feed pump please how much make model and supplier etc
thanks in anticipation
David
___________________________________________________________________________
|| The Live-Aboard List : send a "subscribe" or "unsubscribe" request ||
|| in body of message to: ||
