Buying a Masterline Booster

[Superlyte27]

This is great news! Now I won?t be competing with you if a used one ever shows up for sale!

Man, I am so tired of looking. I look every single day. I paid for Haskell to rebuild my Haskell and 6 months later it's still screwed up. Today, I got the news that I won a contest yielding me $6k, and later discovered my trip to Little Cayman was refunded. So, I'm sick of looking. 5 weeks from now, I'll have my very own masterline

[rddvet]

This is great news! Now I won?t be competing with you if a used one ever shows up for sale!

I waited for 3 years and finally had to give up and buy new. They?re annoyingly hard to find.

[cmck1]

We've been running the new Masterline 7000A-2 (single phase 230V) with the VFD upgrade for 3 months now. It has worked flawlessly. We use it only for 100% and 50% and have a Sierra for other gasses. We are boosting 50% on setting 10 and 100% on setting 7 and it works fine for AL40 and AL80. We do not boost much in the way of the smaller cylinders but it should work fine. Chris was great to work with. Good luck.

[rddvet]

We've been running the new Masterline 7000A-2 (single phase 230V) with the VFD upgrade for 3 months now. It has worked flawlessly. We use it only for 100% and 50% and have a Sierra for other gasses. We are boosting 50% on setting 10 and 100% on setting 7 and it works fine for AL40 and AL80. We do not boost much in the way of the smaller cylinders but it should work fine. Chris was great to work with. Good luck.

Does the vfd give you good fine contol over pumping speed? Is your regulator on the supply bottle wide open or are you controlling it some with regulator pressure?


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[rddvet]

In retrospect I can now see the vid is built into the unit. That’s interesting. That must be a new option since I bought mine a few years ago. I’m still interested to hear what you do with the pressure regulator.

[NorthWoodsDiver]

Hey guys. After dealing with Haskel issues for the last several months, I decided I just couldn't take it anymore. I'm buying a Masterline.

If you have experience with Masterline, can you guys please tell me what options I should look for?

Thanks in advance for your help.

What problems did you have with Haskel or their products? IAfter 8 years at Wakulla Dive Center I played with them a good bit including complete rebuilds on several models. Some more successfully than others....

[rddvet]

What problems did you have with Haskel or their products? IAfter 8 years at Wakulla Dive Center I played with them a good bit including complete rebuilds on several models. Some more successfully than others....

Rebuild costs are what pushed me away from a haskel. The masterline costs $25 at the absolute most for any major overhaul. It costs $9000 but for me the potential service costs of a haskel over the same service life of masterline make the haskel much more expensive in the long run. Of course it depends on which haskel. Seems theres a big difference in service parts unit to unit. My other issue with the haskel is the amount of drive gas. My garage is already packed with the compressor, dive gear, and whatnot for 2 people. I?ve got no room for the size of shop compressor I would need to run the size haskel I would want.


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[tbone1004]

Does the vfd give you good fine contol over pumping speed? Is your regulator on the supply bottle wide open or are you controlling it some with regulator pressure?


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Curious to see what the actual recommendation is.

The VFD will give you absolute control over the motors RPM. If you think of it in percentages of speed, you get control in roughly 5% increments on a VFD that uses a pot to control speed which most do. You get more control if you use a digital speed controller or it has some sort of speed reference, but that's way overkill for this. Pot is more than fine. You will then have speed control with most industrial motors down to about 25%. The VFD is capable of going down to essentially 0, however the motors usually can't keep themselves cool unless they have an aux cooling fan *basically a motor bolted onto the end of them driving the cooling fan which is normally on the main shaft*. So practically speaking you can get to ~25% with no modifications other than putting the VFD on there.

[rddvet]

Curious to see what the actual recommendation is.

The VFD will give you absolute control over the motors RPM. If you think of it in percentages of speed, you get control in roughly 5% increments on a VFD that uses a pot to control speed which most do. You get more control if you use a digital speed controller or it has some sort of speed reference, but that's way overkill for this. Pot is more than fine. You will then have speed control with most industrial motors down to about 25%. The VFD is capable of going down to essentially 0, however the motors usually can't keep themselves cool unless they have an aux cooling fan *basically a motor bolted onto the end of them driving the cooling fan which is normally on the main shaft*. So practically speaking you can get to ~25% with no modifications other than putting the VFD on there.

I didnt even realize you could use a vfd on single phase. I thought it was only to convert three phase to single phase and then also gave you control over motor speed. Long term varying electrical input into the motor doesnt lead to any damage? I know slowing a compressor down long term is better for it, but dont know enough electrical to know if theres any negative effect on the motor long term.


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[tbone1004]

I didnt even realize you could use a vfd on single phase. I thought it was only to convert three phase to single phase and then also gave you control over motor speed. Long term varying electrical input into the motor doesnt lead to any damage? I know slowing a compressor down long term is better for it, but dont know enough electrical to know if theres any negative effect on the motor long term.


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while VFD's can be used for phase conversion, that is not their original purpose. Originally, they are designed to allow AC motors to be used at variable speeds. Historically you would use DC motors when you needed variable speed, but DC motors are huge/heavy/expensive compared to AC motors, so it's much better now that technology allows us to vary the frequency going to the motors.
VFD's can be used for phase conversion since they take AC in, convert to DC, then spit AC back out. Most are made for 3p motors because it is much cheaper to operate so industry almost exclusively uses 3-phase motors. Efficiency is around 85% for 3p vs 65% for 1p which can lead to massive cost savings.
Unfortunately 1p VFD's in the 1.5hp range for 110v are not available to my knowledge. If your motor can be wired for 230v, then there are 1.5hp vfd's out there that will do that.

Practically speaking the motors don't really care. With DC motors when you change their speed, you are changing the voltage going to them which creates massive amounts of heat because the current goes through the roof. With AC drives, you are actually changing the frequency of pulses going to the motors. 60hz is what comes out of your wall in this country, so 60x/second the motor is being hit with power to turn. 50x in most of the rest of the world. With a VFD, you are still hitting it with the same voltage, but you are hitting it less frequently. As long as the motor is running fast enough to keep itself cool *which is why you don't want to slow it down lower than ~25% of speed*, then it really couldn't care less. We have huge industrial fan motors *30-50hp* that have been running on VFD's for ~10 years continuously that are almost never at full speed. Motors are fine.
Single phase motors are often not built for inverter duty though so their lifespan may be reduced, but at the rate you and C are using that thing, you'll probably be out of diving before it is an issue. Even if someone like Wayne was using it, it would be at least 5 years before it was an issue.

In the last couple of years, VFD's have gotten cheap. If you double the HP rating, you can use them for phase conversion. This has made a lot of industrial machining tools more readily available to end-users as the VFD's are cheaper and better than trying to find a big enough single phase motor. Think lathes, drill presses, milling machines, big shop compressors, that often have motors that can be wired for 220/440vac but are all 3-phase. Trying to find a big enough single phase motor is very expensive if they're even available in those hp ratings or frame sizes. VFD's allow you to leave the whole machine intact. It also makes things more convenient for things like lathes, milling machines, etc. where you used to have to use pulleys to change the speeds and only had so much control. With the VFD, you can do rough adjustment with the pulleys, and get fine adjustment with a knob on the front. I converted our massive lathes *36" diameter beasties from the 1950's* to VFD's and my machinists are very happy to not have to deal with changing the gears anymore.