Quick Answer: A socket adapter with stopcock combines three parts in one glass piece: a ground-glass socket, a stopcock tap and a straight tube for rubber tubing. Fitted over a cone joint, it lets a gas, vacuum or drain line be opened and closed right at the apparatus.
Socket End, Tap in Line
Most tubing adapters in a ground-joint kit end in a cone, because they plug into a flask neck. The socket version is for the opposite situation, where the apparatus presents a cone and the adapter slips over it. Cone outlets are found on the lower ends of condensers, columns, drying towers, traps and some reaction vessels. With this adapter on the cone, the tap controls the flow and the straight tube carries the line on to a hose.
Straight connection means the tube leaves in line with the joint rather than at a right angle. That suits a vertical cone where the tubing must hang down to a drain or run on to a line below, and it keeps the flow path short with no corners in which liquid can gather. For flask necks where the tubing must leave sideways, the right-angle cone adapter with stopcock is the matching fitting.
Neither the joint size nor the key material appears in the title. A glass key is run with a light film of grease, whereas a PTFE key is used dry.
Applications
- Closing off the outlet cone of a column, trap or drying tower when it is moved
- Draining liquid from apparatus with a cone outlet into a hose and receiver
- Controlling vacuum or inert gas to a vessel that has a cone connection
- Isolating one branch of a glass gas train during an experiment
Specifications
| Joint | Ground-glass socket that fits over a cone |
| Control | Stopcock tap to open or close the line |
| Outlet | Straight tube for rubber or plastic tubing |
| Stopcock key material | Not stated in the title (glass or PTFE) |
| Joint size and bore | Confirm at enquiry |
Care & Handling
- Turn the tap only while the adapter is supported; force on the handle passes to the joint and can snap the cone beneath.
- Keep each glass key with its own barrel, since keys are ground to one barrel and do not swap reliably.
- Loosen or remove the key for storage, with a strip of paper in the barrel, so it does not seize.
Why Choose LabEquip
Research and teaching labs with gas trains, traps or columns that end in cone outlets use this adapter to add a tap exactly where it is needed. LabEquip includes it in the chemistry lab equipment range; send your joint size and key preference on the contact page.
Frequently Asked Questions
What is a socket adapter used for?
It connects tubing to apparatus that ends in a cone, such as the outlet of a column, trap or condenser. The socket slips over the cone and the tube takes a hose.
Why is there a stopcock in the adapter?
So the line can be closed at the apparatus. You can then disconnect tubing, stop a drain or hold a vessel under gas or vacuum without extra clamps or taps.
What does straight connection mean?
The tube leaves in line with the joint instead of at a right angle. It suits vertical cones where the tubing should run straight down or straight on.
Is a PTFE or a glass stopcock key better?
Each has a place. A PTFE key runs without grease, which keeps solvents clean, though its retaining nut should only be finger-tight. A lightly greased glass key gives a very tight seal for vacuum, but can stick if left unused.
Can this adapter hold a vessel under vacuum?
Yes, when the tap is closed and the socket is greased and clipped onto the cone. Check that the key is fully seated, because a loose key lets air creep in along the barrel.
What tubing fits the straight outlet?
Rubber or PVC tubing for gas and liquid lines, and thick-walled vacuum tubing for pumping. Moisten the glass with water or glycerol first, and grip the adapter near the tube rather than by the tap while pushing the tubing on.
Last Updated: September 2026
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