You are right, you already know thew answer to this but thanks for the opportunity to answer it. The average life expectancy of a membrane I usually qoute is 5-8 years. This after years of working on all kinds of watermakers seems to be a good average. I've seen them last longer and I've seen them go bad sooner even with the best of care. The fact that this membrane is at least 13 years old, had been pickled at one time for five years, and still produced 360-400PPMs when started up again is in my opinion amazing. But I've learned never to say never in this business. Cleaning a membrane, and this may go against conventional thought, is a waste of time, especially one this old. Proper membrane cleaning needs to be done on a routine bases to be effective. It doesn't really make sense for most boat
based watermakers to be on a cleaning routine, it's just easier and more effective to replace the membrane. But even though it's time to replace this membrane there are a few things to check. A 380C is an older model which may have other issues that need to be checked as well. The 380C is still the energy efficient standard all other companies wish they could achieve. Basically a watermaker
works on a balance of pressure and flow across a membrane. If either of these two things are out of balance it will affect both production and PPMs in either direction. Anytime I work
with a Spectra 380C that is having a problem with PPMs I always start with the two feed pumps first. This is where the pressure and flow begin in this particular system. If either of these two pumps is not performing to spec then you will see higher PPMs. First I always check voltage at the units terminals when the system is operating. You want at least 12.5V or 25V at the terminals. Always check connections on an older system. Once voltage is established start one feed pump
, let it operate for at least three minutes first then record
both the pressures on each stroke of the Clark pump
and the flow meter readings on each stroke. Repeat this with the other feed pump running alone as well. Then, with only one feed pump running, pinch off the brine discharge line completely and observe the pressure gauge. The pressures should quickly rise to the 125psi range (give or take 10psi) and the pump should shut off on it's own. If the pressure does not rise to this mark and continues to run at a lower psi threshold then your feed pump head
is worn and needs to be replaced. Of course repeat this with the other pump running alone as well. If both pumps work well then the flow test is pointless and the membrane is bad. If either pump or both pumps are worn then replace them first then decide to condemn the membrane or not.
One of the great things about Spectra is they are truly designed and engineered with the thought of an owner in far flung places needing to do service
work themselves. Though these feed pump heads are proprietary to Spectra they are the easiest ones to replace, especially on a 380C. Two 5/8" hoses (in and out), two wires on spade connectors (non directional) for the pressure switch provided, and three screws (new ones provided with the new feed pump head
with loctite). Provided your system is not buried in the bowls of the boat it should take about ten to fifteen minutes to change it out. The membrane is not hard at all. Spectra makes the best membrane vessel to work on in the industry. On your 380C Spectra uses the flexible high pressure hose line which does not need to be removed. You should be able to spin off the end cap ring with hand pressure alone. After sitting for 13 years it might need a bit of gentle persuasion but it will thread back on and hand tightened down. No special tools, O-rings that shift on installation
, nuts, bolts wires, etc. You know how to get a hold of me if you need advice. I always enjoy interacting with fellow CF members, they tend to get a little better special treatment.