First, just put more whips on the Hyperfilter - it has three ports. You can easily attach three final whips and just fill 'em up.
Yes, you should be able to fill a bank with this compressor. It runs VERY cool - head temperatures are in the "quite warm but not blistering" range, even after running an hour or so. While I don't know that I'd call this unit "continuous duty", I bet if you pointed an auxiliary fan at it to keep the temps down a bit more you'd get away with it. It IS low RPM (1200); comparatively to other units of this size class that's not running very hard at all!
But let's think about the bank requirements here a bit, because I think you're in for a rude surprise.
A 400 cuft 4500 psi bank tank would require about 2 hours to fill from bone dry. A 3500 psi HP120 is a bit more than one bank tank can fill from full pressure and reach final if empty (it will end up at 3461 psi), so you've got a MAJOR storage problem doing this - you're going to need a LOT of storage tanks filling HP steels like this. Let's say you have four of those 400 cube tanks in a bank. If you start empty with 10 HP 120s, you've got 1200 cuft of gas volume to add. Doing the math, you're going from 1600 cuft of volume to 2800 cuft; the pressure goes from 4500 to 2571. From there there you'll have to run the compressor to top them off. I don't know that you're saving enough here to be worthwhile; if you attempt to recharge the bank at the same time you've more than doubled the top-off time!
If you were to rig the bank as a cascade, you can do better, but now the plumbing gets more complex.
Why are you filing 10 or 12 tanks a night? This is for three or four guys? If so, you probably want a bigger unit. I'd probably be looking at their W31-2, wich is TWO of these blocks in a cabinet with one motor.
I figure that filling four tanks in an evening is acceptable and this unit will do that in an evening without being significantly burdensome. Beyond six tanks in an evening I'd say its not enough.
An auto condensate drain is doable. This unit has two purges, so you'd need a high pressure pilot valve for the final stage, and the low-pressure one on the moisture separator is then solenoid activated. The idea here is that when the timer fires, the low pressure solenoid valve actuates, which collapses the air supply in the pilot valve and it opens on the high pressure side. The timer would be pretty easy to construct. If you use a normally-open solenoid valve, and connect it into the mag starter, you now have an automatic unloader that operates when the unit shuts down. If I was to do this I'd consider putting in an outboard filter stack and using the existing one as a second-level moisture separator ONLY - the reason for this is that you could then (with check valves) leave the stack pressurized when the unit shuts down, which will save you considerable time if you shut down between tanks when filling - it takes a couple of minutes to recharge the Lawrence Factor filter on my unit before any gas flows!
If you're going to run this unattended you'd need a magnetic starter and final pressure switch, so that it will shut off on its own, and the auto drains. If you're continuous blending unattended then you need MUCH more safety stuff, including a soenoid on the O2 feed so if the power goes off or the compressor shuts down the O2 flow is killed - otherwise you're asking for a nice "boom" if there is a power interruption! There is a packaged version of this unit with two of these compressor blocks run off one motor, in a cabinet, that has all this already in it - its more expensive, but might be a beter choice, as it also has twice the output. The only issue would be figuring out the power - don't know if its available in a single-phase drive or not - and integrating a continuous blending system if you intend to use one.
That would give you 7 cfm, which would fill 10 tanks in about two and a half hours of runtime, assuming they're not completely empty when you start. That's tolerable, and with the volume you're talking about I'd go that way.
Yes, you should be able to fill a bank with this compressor. It runs VERY cool - head temperatures are in the "quite warm but not blistering" range, even after running an hour or so. While I don't know that I'd call this unit "continuous duty", I bet if you pointed an auxiliary fan at it to keep the temps down a bit more you'd get away with it. It IS low RPM (1200); comparatively to other units of this size class that's not running very hard at all!
But let's think about the bank requirements here a bit, because I think you're in for a rude surprise.
A 400 cuft 4500 psi bank tank would require about 2 hours to fill from bone dry. A 3500 psi HP120 is a bit more than one bank tank can fill from full pressure and reach final if empty (it will end up at 3461 psi), so you've got a MAJOR storage problem doing this - you're going to need a LOT of storage tanks filling HP steels like this. Let's say you have four of those 400 cube tanks in a bank. If you start empty with 10 HP 120s, you've got 1200 cuft of gas volume to add. Doing the math, you're going from 1600 cuft of volume to 2800 cuft; the pressure goes from 4500 to 2571. From there there you'll have to run the compressor to top them off. I don't know that you're saving enough here to be worthwhile; if you attempt to recharge the bank at the same time you've more than doubled the top-off time!
If you were to rig the bank as a cascade, you can do better, but now the plumbing gets more complex.
Why are you filing 10 or 12 tanks a night? This is for three or four guys? If so, you probably want a bigger unit. I'd probably be looking at their W31-2, wich is TWO of these blocks in a cabinet with one motor.
I figure that filling four tanks in an evening is acceptable and this unit will do that in an evening without being significantly burdensome. Beyond six tanks in an evening I'd say its not enough.
An auto condensate drain is doable. This unit has two purges, so you'd need a high pressure pilot valve for the final stage, and the low-pressure one on the moisture separator is then solenoid activated. The idea here is that when the timer fires, the low pressure solenoid valve actuates, which collapses the air supply in the pilot valve and it opens on the high pressure side. The timer would be pretty easy to construct. If you use a normally-open solenoid valve, and connect it into the mag starter, you now have an automatic unloader that operates when the unit shuts down. If I was to do this I'd consider putting in an outboard filter stack and using the existing one as a second-level moisture separator ONLY - the reason for this is that you could then (with check valves) leave the stack pressurized when the unit shuts down, which will save you considerable time if you shut down between tanks when filling - it takes a couple of minutes to recharge the Lawrence Factor filter on my unit before any gas flows!
If you're going to run this unattended you'd need a magnetic starter and final pressure switch, so that it will shut off on its own, and the auto drains. If you're continuous blending unattended then you need MUCH more safety stuff, including a soenoid on the O2 feed so if the power goes off or the compressor shuts down the O2 flow is killed - otherwise you're asking for a nice "boom" if there is a power interruption! There is a packaged version of this unit with two of these compressor blocks run off one motor, in a cabinet, that has all this already in it - its more expensive, but might be a beter choice, as it also has twice the output. The only issue would be figuring out the power - don't know if its available in a single-phase drive or not - and integrating a continuous blending system if you intend to use one.
That would give you 7 cfm, which would fill 10 tanks in about two and a half hours of runtime, assuming they're not completely empty when you start. That's tolerable, and with the volume you're talking about I'd go that way.
Let me think about this..... Nitrox for roughly $2/tank in costs, .vs. buying it for $10.... hmmmm.... I wonder when I'll get tired of that 
