Specifications

Three‑Way Stopcock · Specifications

Standard sizes are listed below. All products comply with GB/T, ASTM, and ISO standard taper systems. Full range 10/19 ~ 60/45 available. Custom bore diameters, plug materials, and configurations are available.

Request custom specs

1. T‑Port Stopcock (Standard Bore)

Bore (mm)	Plug Diameter (mm)	Plug Length (mm)	Body Length (mm)	Arm O.D. (mm)	Arm Length (mm)	Plug Material
Please contact us to confirm the available specifications.

2. T‑Port Stopcock (Capillary Bore)

Bore (mm)	Plug Diameter (mm)	Plug Length (mm)	Body Length (mm)	Arm O.D. (mm)	Arm Length (mm)	Plug Material
Please contact us to confirm the available specifications.

3. Standard Joint Three‑Way Stopcock

GB/T	ASTM	ISO	Arm Length (mm)	Plug Material
Please contact us to confirm the available specifications.

4. Three‑Port Vacuum Stopcock (Vacuum Series)

Plug Diameter (mm)	Plug Length (mm)	Arm O.D. (mm)	Arm Length (mm)	Plug Material
Please contact us to confirm the available specifications.

* Bore sizes 2mm ~ 10mm available; straight or capillary bore options.
* Joint numbers (14#, 19#) indicate the largest diameter (mm) of the taper. All are 1:10 taper.
* GB/ASTM/ISO designations are different standard identifiers — physical dimensions are identical and fully interchangeable.
* Full range 10/19 ~ 60/45 available upon request.
* Double‑oblique and 120° oblique configurations available upon request.
* Contact our sales team for MOQ and lead time on custom orders.

✦ Customization Services — We offer custom bore diameters, joint sizes, plug materials, and configurations. Share your specific requirements and our technical team will provide a tailored solution.

Product Description

The three‑way stopcock is a critical flow control component for switching among three flow paths in standard taper glassware systems. Its design consists of a glass body with three arms arranged in a T configuration and a tapered plug featuring a T‑shaped bore. By rotating the plug, operators can direct flow through different combinations of ports, making it an indispensable component for Schlenk lines, vacuum manifolds, and multi‑port reaction systems.

Key Features

Borosilicate Glass 3.3: Meets GB/ISO/ASTM standards, low thermal expansion, thermal shock resistance up to 280°C, excellent resistance to most acids, bases, and organic solvents
Multi‑Standard Compliance: Precision‑ground 1:10 taper meets GB/T, ASTM E, and ISO 3585 standard taper specifications, guaranteeing full interchangeability with all major standard systems
Dual Plug Materials: Glass plug (resistant to most organic solvents, cost‑effective) or PTFE plug (resistant to strong acids/bases, no lubrication required, superior seal)
Versatile Bore Options: Straight bore (2mm ~ 10mm) for liquid flow control; capillary bore available for precise gas flow regulation
Multiple Configurations: T‑port (standard), double‑oblique (two 45° bores, 180° rotation for port switching), 120° oblique (conforms to DIN 12563)

Quality Assurance

Each three‑way stopcock is inspected for taper accuracy, T‑port alignment, and seal integrity to ensure smooth operation and leak‑free closure. Custom bulk orders are welcome.

Tip: Always check plug rotation before use. Glass plugs may be lubricated with a thin layer of vacuum grease; PTFE plugs require no lubrication. Rotate gently to avoid glass breakage.

Applications

Typical Uses

Gas/Liquid Flow Switching

Select and direct flow paths among three lines

Schlenk Line Systems

Switch between N₂/Ar purge and vacuum evacuation

Vacuum Manifolds

Independent control of multiple vacuum branches

Distillation Apparatus

Multi‑port control for fraction collection

Teaching Labs

Fundamental flow control for organic/inorganic courses

Compatible Equipment

Standard joint flasks, condensers, distillation and fractionating heads

Schlenk lines, vacuum manifolds

Inert gas (N₂/Ar) supply systems

Vacuum pumps and vacuum lines

Tip: Always use matching standard joint sizes for optimal sealing. Three‑way stopcocks can be used independently or combined with other standard joint components.

Operation & Maintenance

User Guide

Before Use

Inspect for cracks, chips, or scratches on any joint
Check that the plug rotates smoothly and the T‑port aligns properly
Clean all joint surfaces with a soft cloth to remove particulates
For glass plugs, apply a thin layer of vacuum grease to the contact surfaces

Switching Operation

Rotate the plug to the desired position for the required flow path
T‑port stopcocks switch among three lines by rotating the plug
Double‑oblique stopcocks switch between upper and lower ports with 180° rotation
Rotate gently; avoid excessive force

Installation

Align the joint with the receiving port and gently twist into place
Use a clamp on the body of the stopcock (not on the arms) for support
For vacuum applications, verify the stopcock is in the correct position and test seal integrity

Cleaning & Storage

Clean immediately after use to prevent bore blockage
Use soft brushes and appropriate detergents for the arms and T‑port bore
Air dry and store with protective paper between ground joints
For long‑term storage, remove the plug to prevent seizing

Three‑Way Stopcock · Selection Guide

Four key dimensions determine the right three‑way stopcock for your system: plug material, bore size, bore type, and configuration.

1. By Plug Material

Glass Plug (Standard): Resistant to most organic solvents, cost‑effective. Suitable for routine organic synthesis and distillation.
PTFE Plug (Upgrade): Resists strong acids, bases, and aggressive chemicals. No lubrication required, superior seal. Ideal for harsh chemical environments.

2. By Bore Size

Bore Size	Typical Application
Please contact us to confirm the available specifications.

3. By Bore Type

Straight Bore: Standard through‑hole for general liquid and gas flow switching
Capillary Bore: Precision small‑diameter bore for fine gas flow regulation and distribution

4. By Configuration

Configuration	Features	Typical Application
Please contact us to confirm the available specifications.

5. Quick Selection Checklist

Follow this decision flow to quickly identify the right configuration:

① Media type? Organic solvents → Glass | Acids/bases/corrosive → PTFE
② Flow rate? Low → 2~4mm | Medium → 6~10mm
③ Media state? Liquid → Straight bore | Gas → Capillary bore
④ Switching mode? Standard 3‑port → T‑port | Bidirectional → Double‑oblique | ISO system → 120° oblique | High vacuum → Vacuum series

✦ Need help selecting? Contact our technical support team with your experimental conditions and connection requirements — we'll recommend the optimal configuration.

Care & Notes

Show care & notes

Safety Precautions

Always operate in a fume hood when handling flammable or toxic substances
Verify stopcock seal integrity and port status before applying vacuum
Wear protective gloves and safety goggles

Do not

Never use cracked or damaged stopcocks under vacuum or pressure