DOS pump tubing life and replacement? Hours or Rotations?

[Jamie814]

DOS and DOSQD Why doesn't Neptune have some way to determine when it is time to replace the tubing on these pumps? I do not see any specific information on tube life. Using hours is not useful to determine tubing life when the pump can run at all different speeds.

Can't they write some programing to read the approximate rotations/speed to calculate when and inform the user that it is time to replace the pump head? I have seen several threads online where a tube or head failure has caused tank crashes/floods when using this pump on a AWC, top off or calcium reactor.

Just my $.02

 

[Formulator]

The pump speed on the DOS is constant, so its really just a matter of volume dosed, which is essentially the running time of the pump. I’ve heard on the Neptune forums to replace every 500 gallons. If you know your daily dose, you should be able to work out how long it will take you to get to 500g.

That said, I agree it would be nice to have an alert in the software and it seems easy enough to do. Not sure why they haven’t…

 

[Jamie814]

The pump speed on the DOS is constant,

The speed is variable, so I assume you mean the dose is constant per revolution.

I just seen Neptune stating themselves the motors are rated for 5,000 hours, which from a technical standpoint doesn't make sense because the speed is variable. There is going to be a lot more motor wear per hour of running at 1ml/min verses 100ml/min.

The DOS knows how much volume it is pumping so a simple software update should be able to calculate tube life based on volume dosed over time... @NeptunePaul

 

[Formulator]

The speed is variable, so I assume you mean the dose is constant per revolution.

I just seen Neptune stating themselves the motors are rated for 5,000 hours, which from a technical standpoint doesn't make sense because the speed is variable. There is going to be a lot more motor wear per hour of running at 1ml/min verses 100ml/min.

The DOS knows how much volume it is pumping so a simple software update should be able to calculate tube life based on volume dosed over time... @NeptunePaul

Actually I did not realize the speed was variable. You’re sure about that?

 

[areefer01]

Submit a ticket and in the body make a suggestion of what you are asking. Doesn't hurt.

For the record Neptune suggests 700 hours of run-time for replacement of the DOS headcap. Venture to Neptunes replacement parts page, screen cap below. Auto water change headcaps are going to be replaced more frequently than say someone dosing in smaller rotations.

This isn't difficult for a hobbyist to manage to be honest. Installation runs a calibration so just used the note option in the Apex saying installed, calibrated, and be done. Every six months run the calibration to check and add another note. This way you can keep track. Depending on what you are doing you now know dates and timeline of use.

TL; DR I understand you want a UI trigger but since there isn't one send a note / suggestion and manage by your note keeping and calibration verification.

 

[Jamie814]

For the record Neptune suggests 700 hours of run-time for replacement of the DOS headcap.

I'd like to know how they came up with this number and at what dosing speed?

The DOS QD runs at 7 ml up 60 ml per minute continuously but at different rotation speeds or revolutions per minute.

Based on Neptunes suggestion it means you should be changing the pump heads monthly, 700/hours/24/day = 29 days which would be very expensive to operate.

 

[areefer01]

I'd like to know how they came up with this number and at what dosing speed?

Reach out to them and ask.

Based on Neptunes suggestion it means you should be changing the pump heads monthly, 700/hours/24/day = 29 days which would be very expensive to operate.

If that is continuous then yes, the math would pan out as an estimate. Replacement intervals depends on use case and it will vary for each hobbyist. Look up GHL's replacement intervals - they don't' give a number only general indicators. Thus my comment about keeping notes, running calibrations for checks, and go from there.

The calibration task is pretty simple to run and will give you an indication of dosing accuracy. I always recommend keeping spare parts so have a couple heads tucked away. This works for me. I understand some hobbyist may have different needs so maybe shop around and see if there is anything better suited to their installation.

 

[Formulator]

The DOS QD runs at 7 ml up 60 ml per minute continuously but at different rotation speeds or revolutions per minute.

The DOS does not run continuously. Unless you have set it up that way, though I’m struggling to imagine that application…

 

[Jamie814]

The DOS does not run continuously. Unless you have set it up that way, though I’m struggling to imagine that application…

The new DOS QD runs continuously at speeds less than 25ml/min and is what I am using on my CA reactor now. I use both heads, one runs 24/7 and the other head doses additional effluent during daylight when CA/ALK uptake is higher, and pH tends to be higher helping to offset the lower pH from the effluent.

This is why I am trying to figure out how long the tubing should last and be proactive before it cracks and starts to leak which is how peristatic pumps generally fail first.

"Continuous Duty Operation: At speeds up to 25 ml/min, the DŌS QD can run continuously, allowing the pump heads to run more quietly and offering more flexibility for additive dosing and automatic water changes."

 

[Formulator]

I think we are on the same page. I thought you were saying it only runs continuously and only controls the dose volume by varying pump speed. My understanding is that It can run continuously, but that is not the default setting. It sounds like a neat feature, with the drawback of short pump life as you calculated above.

I work in drug product manufacturing process development and we use peristaltic pumps for almost all of our liquid handling, including vial filling, which uses similar diameter tubing to our DOS pumps. Continuous operation is typically limited to 24 hours or less before SOPs require tubing change-out to avoid catastrophic failure. In the lab, I won’t run for more than 4 hours because I’ve had tubes burst and its not a fun experience (not to mention the cost of whatever I am pumping, sometimes worth upwards of $500/mL).

So it seems either Neptune doesn’t understand their own product very well (wouldn’t be the first time in our hobby), or they just expect their customers to buy a new pump head every month or so. Or perhaps they have used some kind of durable material for their tubing other than standard silicone. If you figure out what kind of tubing, I wonder if you could cheat by taking the head apart and just replacing the tubes once/month.