Maintenance of Oily Water Separator (OWS)
when the OWS fails, the consequences can be serious. Not just for the ship, but for your licence, your freedom, and your reputation.
So, instead of waiting for alarms and PSC surprises, here are 7 practical tips to help keep your oily water separator running smoothly.
1. Understand What You’re Working With
Every OWS system is a little different. Some use simple gravity and coalescers. Others are more advanced with filters and chemicals.
Why it matters: The wrong cleaning method or setting can mess things up.
Your move:
- Read the manual (yes, the actual one).
- Don’t just go by what the last guy did.
- Know your model and how it’s meant to work.
2. Keep the Coalescer Clean – It’s the Core of the System
Think of the coalescer like the lungs of your OWS. If it’s dirty or clogged, the system can’t breathe.
What happens:
- Separation becomes inefficient.
- OCM starts throwing alarms.
- You risk crossing the 15 ppm limit.
Your move:
- Clean it on schedule (don’t wait till something goes wrong).
- No high-pressure water—just gentle cleaning.
- Replace if swollen, cracked, or falling apart.
3. Watch the Oil Content Meter Like a Hawk
The OCM is your digital conscience. It tells the truth, even when it hurts.
What it does:
- Samples every drop leaving the OWS.
- Triggers alarm if oil content exceeds 15 ppm.
- Logs everything for port state to see later.
Your move:
- Clean the lenses gently.
- Calibrate it as per the manual or Class rules.
- Check that alarms and auto-stop work as they should.
4. Test the Auto-Stop System Every Month
This one’s a lifesaver. Literally. If oil levels go above 15 ppm, the auto-stop must shut down discharge instantly.
Your move:
- Simulate a high oil reading and test the system.
- Make sure it actually stops the pump.
- Record the test in your PMS or engine log.
If it doesn’t work—fix it now, not later.
5. Don’t Ignore the Pipes—Back pressure Can Ruin Everything
We often check the separator, but forget the lines. Don’t.
What can go wrong:
- Overboard valve closed? Backpressure builds.
- Dirty lines? Flow drops, alarms go off.
- Overflow risk in bilge tanks.
Your move:
- Clean discharge lines regularly.
- Always check overboard valves before starting.
- Install pressure gauges if not already there—it helps.
6. Log Everything in the ORB
Your Oil Record Book isn’t a formality. It’s your legal safety net.
What to log:
- Date and time of discharge
- Quantity processed
- Start and stop times
- Any OWS-related maintenance or alarms
Pro tip: Don’t log it later. Don’t copy-paste. What’s written must match the OCM memory.
7. Teach the Juniors
Let’s face it, OWS often runs when no one’s watching—during night watch or port stay. And that’s usually when a junior is in charge.
Your move:
- Walk them through the process.
- Explain why we care about 15 ppm.
- Show them what can go wrong—and how to react.
The more they understand, the fewer surprises you’ll face later.
Quick OWS Maintenance Checklist
☑️ Coalescer clean and in good shape?
☑️ OCM working, calibrated, and not dusty?
☑️ Auto-stop tested this month?
☑️ Overboard valves open and verified?
☑️ Discharge lines clear?
☑️ ORB filled up with real entries—not fiction?
☑️ Junior engineers trained and confident?
