I've been trying to get an answer for this for years.

What does everyone do with their used compressor and vacuum pump oil? Its challenging to get a straight answer regarding what to do.

The most common answer suggests blending it with used motor oil so it's darker in colour. Then taking it to some oil drop off location like an auto store or household hazardous waste location. But I've read that those oils shouldn't be blended.

I've taken it to a hazardous waste location and told them it's refrigeration oil, and they're telling me commercial products aren't accepted.

We produce maybe around 50 gallons a year, so getting set up with a commercial recycling seems excessive.

I definitely don't want to dump it down the drain.

Does the compressor force because it makes frost like snow and it heats but it's not hot it's an R600a

I try to clean up the wiring a bit when I do these types of simple replacement jobs

Hello all, got approved by the state and awaiting a test date to go for my license. Been using website and doing practice questions every night. Going well so far. How many questions are on the test? And do they provide a PT chart to reference for some questions? If anyone has recently taken the test, I’d greatly appreciate some insight so I can prepare the best that I can so I can pass on the first try. Thank you

We had about 45 lbs of 507 at the shop. Labeled as "wet".

I'm drawing it off the liquid side, through the drier and sight glass and back into the vapour side.

Has anyone given this a try before? I'm wondering how long it might take to start reading dry. If that's possible.

I'd hate to toss it out.

This was a wild ride of a call I had yesterday.

Called for evap being frozen over. Unit didn't shut off from temp control. Defrost not shutting it down either.

Turned off unit to dethaw from breaker came back next day and then wouldn't come back on.

Rat's tail was a point of contact and a lug on the condenser breaker was the other.

Pretty sure the manufacturer ran the wire between the hot well and the unit's wall. That or over the 10 years of running it popped up in there.

I build hardware, and have a friend that's a Refrigeration technician. He asked if I could build him a monitoring device. Basically he wants a device that tracks the temperature of his fridges, and if the doors are being open/closed and have access to said data on the cloud.

He has quite a few customers and sees value in tracking their systems. He does normal fridges and also industrial systems (some of which have to work) but it's pretty ad-hoc, people call him up and he just fixes these systems, no installs or anything.

I got interested because this seems like a product opportunity, but I wanted to ask some more experts. Does anyone use anything like this already? Or is this generally something very few people need or want?

Thanks!

Hello, just started branching into refrigeration from large commercial and my company has been taking on all grocery equipment including the smaller restaurant cold line units. Installed a compressor earlier this week and had a slight pressure drop of 0.3 PSI after 30 minutes. I understand that a warm compressor can cause pressures to lower after install but when it comes to total refrigerant being in the ounces just how much is too much loss on psi?

Heard about this on the radio, what a mess!!

When should one move on from a shop? If one wants to move to the union as an apprentice? If one works with apprentices and not much with Journeyman’s or doesn’t work on Refrigeration are you being sidelined or is that normal?

In commissioning industrial ammonia and CO₂ refrigeration projects, we often see ICM motorized valves with perfectly good hardware, yet system pressure and liquid level keep fluctuating. Many people's first reaction is to suspect a faulty valve or controller. In reality, quite a few cases trace back to an oversized valve forced to operate long-term in a tiny opening range. This is not a valve quality defect; it's a system matching problem.

The ICM uses a V-notch regulating plug. Plug travel and flow rate are not linearly proportional. At small openings, an extremely slight movement of the plug causes a dramatic change in refrigerant flow; at large openings, the same plug travel produces a much gentler flow change.

When the valve is oversized and actual system load is low, the valve is forced to maintain 5% opening or even less for extended periods (for DN100–150 sizes, the recommended minimum opening is above 10%). The external EKE series controller's PID loop outputs adjustment commands based on pressure or level deviation, asking the ICM to fine-tune its opening. But the slightest plug movement swings the flow drastically — overshoot is almost inevitable: too much flow when opened a touch, then instantly too little when closed a touch. The controller can only keep correcting back and forth, which manifests as oscillating system pressure and level.

Secondary symptoms follow: the ICAD actuator frequently triggers the Boost function, the valve position keeps correcting back and forth, the event log fills with A9 valve position deviation alarms, and mechanical wear on the motor and plug seals accelerates.

Here's the key point: valve selection must not simply copy the site pipe DN size. You must calculate the Kv flow coefficient for actual operating conditions and match the function module, ensuring the valve still operates above the manufacturer's recommended safe opening even at minimum system load.

If a project already has this problem, the preferred fixes in order: first, replace with an internal function module with a smaller Kv value — the valve body itself can stay, no pipe cutting needed; second, optimize the controller PID parameters to reduce response sensitivity; third, use the ICAD software to limit the valve's minimum working opening, keeping it out of the dangerous small-opening zone.

— Wenzhou Phonetoo (en.phonetoo.cn), Danfoss IR distributor. Happy to compare field notes.

Had 2 of these old timers from 1985 go down on friday. Oil pressure differential safety tripped. Both units have a set of hot gas bypass with 2 txvs and 1 compressor single circuit, 60 tons with 2 unloaders with 3 heads. Both sets of hot gas bypass valves are stuck wide open, removed power from the in coming solenoid valves to keep them closed. The compressor oil sump was foaming and now it’s solid and steady. Still kept them running.

Are they for capacity control or safety valves

Has anyone taken the alaska mechanical administrator exam for unlimited refrigeration? Or if not in Alaska maybe another state has a similar exam. I’m curious how hard it is. PSI provides a test bulletin listing the topics on the test but besides those basic categories I am not sure what to study. I have been having AI write me up practice tests but they seem too easy. I’ve worked around industrial refrigeration systems for a few years and have an engineering background but am by no means an expert.

Hello everyone,

Does anyone have any references or technical material for calculating the diameter of a vertical wet suction riser in an ammonia refrigeration system?

I need to size a riser for a freezer with a refrigeration capacity of 303,000 kcal/h, an evaporating temperature of -42°C, and a vertical lift of 5.2 meters.

Any help, calculation methods, or references to IIAR guidelines would be greatly appreciated.

Thanks in advance!

I have a KM-650MAH I’ve been using for over 10 years and recently water is being backed up from the drain hole in the ice bin mixing with the ice and melting it so I don’t have enough ice for the day.

I looked at where the drain pipe ends and it’s draining fine.

The guy who fixes my ice machine said it’s because the ice machine sits lower than the drain pipe and to install two separate pipes from the top and bottom to the drain pipe? But like I said I’ve been using this fine for 10+ years so I don’t know why it would be having a problem now.

If anyone could help me out that’ll be great

Thanks