I’ve occasionally wanted to try snowmaking at home on brutally cold days.
Any tips for someone wanting to try this at home? Let’s assume that I have access to tap water at 60psi dynamic pressure and air at 90psi and 10 SCFM continuous (more for short bursts if needed).
My only concern would be that your water pressure isn't high enough. In commercial systems, the air pressure is at 90-120psi, but the water pressure usually at a minimum 250psi (and sometimes as high as 900psi).
When the water pressure drops below the air pressure, you get what we called "the helicopter", where the snowgun pulses and makes a "whomp whomp whomp" sound (like a helicopter).
I have always assumed this is happening because the air and water are "fighting" each other and instead of getting a constant stream of mixed air/water you are getting a period of water only, then a period of air only. The snowgun will actually bounce up and down. We'd run into this a lot when trying to turn down the water really low on days where the temperatures were very marginal.
I have heard of people using pressure washers to up their water pressure.
That's pretty cool that they are selling "external mix" plans/kits. Snowmaking (at scale) is incredibly energy intensive and over the last few years many resorts have been moving towards various "low-energy" gun designs, which basically means external mix.
They definitely don't make as good snow at marginal temperatures but it's impressive what they can do given a lot use 1/20th of the compressed air compared to a tradition air/water snowgun.
A tradition air/water gun is just an 1.5" air inlet, a 1.5" water inlet, a mixing chamber and a nozzle. At higher temperatures, they take an incredible amount of air. We had a few guns that could take 300 horsepower worth of an air compressor, each, to run at -2.5 celsius wet bulb. As is gets colder it gets a little more efficient.
There are some designs that are basically the same but incorporate a "baffle" that attempts to cut down the size of the mixing chamber when there's a high air/water mixture to make them more efficient, but those baffles would often get stuck open, making them useless.
A fangun is the style of snowgun that uses a giant electric fan to project the snow out from the gun. There is an onboard electric air compressor hooked up to a few nozzles that spray out a mixture of air and water. The tiny droplets freeze into the "nucleus" (a tiny ice particle), which other droplets from water-only nozzles bind onto and freeze, creating a "snowflake".
An external mix gun is basically a fangun, minus the big electric fan, and suspended 30+ feet in the air on a pole. A small number of nozzles spray out an air/water mix, creating the nucleus, and then water only nozzles spray out droplets that then bind to the nucleus. It works but needs to be a bit colder, and they are much more susceptible to winds (especially cross winds). If winds don't allow the two types of sprays to mix, you get a nice skating rink instead of snow!
That was a great summary of the tech. Your height comment helps explain why my external mix setup didn’t produce as much snow as it did frost. I only had it about 8’ off the ground.
This coming winter I may try increasing the height of the mixer and positioning a fan underneath to help push the mix upward to give it more time to bind to the nucleus crystal.
Any tips for someone wanting to try this at home? Let’s assume that I have access to tap water at 60psi dynamic pressure and air at 90psi and 10 SCFM continuous (more for short bursts if needed).