Hi There, There seems to be a lot of confusion about installing a new double bottoms cylnder.

METAL CASING What if you pull out the old jack and there is no casing and the standard drawing show casing but the spec is not clear, do you install casing, do you put a bottom in it also, is the bottom only cement that is poured in after.

PLASTIC CASING Some companies use differant types of plastic for there cylinder casing like PVC put together with cement and HDPE that has some electrofusion machine for joints and not sure of how that works. Also have never hears of anyone using the water sensor with the unit.

BACKFILL Some companies use 3 feet of sand to pin the jack at the bottom after getting the casing plumb but then the monitoring pvc pipe are covered in sand, they have a small pipe at the top that is presurized with air and long pipe to bottom of jack but it is covered in sand how does that work for monitoring, how much air presure is used and what risk is that to damage of the casing.

UNION GUARD Some companies use union guard and spend around a grand or more for the goo and have a pipe at the top to monitor for any water and to check if the level changes, sound the best but no way to pin the jack at the bottom because no sand is used because that stuff is just thick goo and a jack can move around out of plumb if forces in one direction.

Would some seasoned repair mechanic please help me with some of the answers to my questions above. I have seen many repair mechanics strugle with these questions also.Thanks again for your help. Jim

-- Jim (elevator555@hotmail.com), September 07, 2004

Answers

Jim,

METAL CASING - The purpose of the metal casing for the hole, is to prevent it from collapsing before the plunger/cylinder can be set. It is customary to put concrete in the bottom after the casing is set to preven anything from washing up into the hole.

PLASTIC CASING - It is almost unanimous across the board for a new installation to have a pvc sleeve around the cylinder, some with the tube to check for water inside the pvc or to pressurize it. This protects the cylinder from items in the hole and electrolysis. In a cylinder replacement, sometimes the hole is not big enough to get a cylinder with PVC around it back into the same hole and manufaturers provide coatings and wraps to protect the cylinder.

BACKFILL - In the old days, after the cylinder was set it was backfilled with sand all the way to the top, to prevent the cylinder from moving, now it is still customary to backfill, but usually its only a couple of feet and then blocking is put over the hole and concrete is poured to cover the hole.

UNION GUARD - This is a product that can be added for additional protection when you use the pvc sleeve. It is poured between the pvc and the cylinder.

Good luck

-- John (elvtech@hotmail.com), September 14, 2004.

How long have you been in the buisness. Do you wever figure it out on your own???

-- (Liftguy@hotmail.com), September 23, 2004.