Utility Pump Hook Up Question

Hi Everyone,
I have a simple question regarding hooking up a direct mount sink pump.

I am using the model and directions found HERE

My question is in regards to coming off of the threaded drain body. Do I have to use a tail piece set up or can I just use a 1 1/2 PVC coupler? The Coupler set up would work best, because it would allow me to just screw the female end to the strainer body and on the other end I can connect my PVC Solvent Union and continue with the rest of the assembly. My worry is whether or not the coupler set-up would be prone to leaking vs the tail piece set up. Thanks for any advice.

The threads on a sink drain are NOT intended for a fitting. They will either not screw into the fitting or it will leak if you do screw it in.

Ok...so the threads on the female coupler fitting must be different or not make as good of a seal as the threads on the tail piece nut? So if I have a sink drain similar to this ONE and I cannot just screw a female coupler onto the bottom of that and I instead need to use a tail piece like the one shown in the picture. How do I then get the bottom of the tail piece to fit into a 1 1/2 inch Solvent Union. The tail piece pipe is too small...I imagine there is a coupler that will transition the bottom of the tailpiece from its current size to 1 1/2 but I can't seem to find it anywhere. Thanks.

I believe you are looking for a trap adapter, though I don't know if I would do that if it needs to support the weight of the pump.

I'm amazed that they make a pump like that- it will have to run every time an ounce of water hits the drain. I hope this is not for a laundry sink.

That is my concern...holding the weight of the pump. Which is why I thought the threaded coupler directly to the drain would be best as the tailpiece assembly seems rather weak with regards to holding the weight of the pump. The pump system is or from what I have researched quite effective...this is for a bar sink in my basement, closes drain was across the room, so I had to run drain pipe up the wall and once I was in the ceiling joists I have a gravity feed down to the main drain stack. But, you are right, the pump will activate anytime water goes down the drain.

EDIT: Found this to be interesting, this is another brand direct mount pump and they show that you actually screw the pump inlet right to the drain body.
LINK

One of these is not much bigger, and is not as likely to self-destruct if someone drops something down the drain.
I use one in my own basement.

http://www.libertypumps.com/Data/SalesLiterature/404.pdf

Yes...I've considered similar set ups, but they have to be vented and hooking to a vent is not an option at this point. Dry wall and bar cabinets are already up.

The "direct connection" pump has a slip nut and tailpiece as part of its assembly, which is entirely different than trying to screw a fitting on the drain.

The pump I have (which I reference in the first post) states this: NOTICE: If the sink-drain tail piece is not 1-1/2" NPT, you will have to adapt it (bushings, reducers, etc.). In this case, wrap all joints with teflon tape before making connections.

My pump came with no such tail piece in the box.

Now, I'm not a plumber, but from what I understand NPT means the piece should be threaded. The bottom part of my drain is 1 1/2 and is threaded. If I connect a tailpiece to this, I end up with an end that is not NPT, so I then need to use another adapter to get back to the 1 1/2 NPT. This doesn't seem to bode well for holding up a 16 pound pump. Other direct mount pumps refer to them screwing directly to the threaded drain bottom...thought maybe this one could do the same.