Specifications

Two‑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. Straight‑Bore 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. Oblique‑Bore 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.

3. Standard Joint Two‑Way Stopcock

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

* Bore sizes 2mm ~ 20mm 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.
* Bent‑outlet configurations available for stopcock bottles and special applications.
* 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 two‑way stopcock is a fundamental on/off flow control device in standard taper glassware assemblies. Its basic design consists of a glass body with two symmetrical straight arms and a tapered plug with a straight‑through bore. When the bore aligns with the arms, the flow path is open; rotating the plug 90° closes the path by misaligning the bore with the body wall. This simple yet reliable mechanism makes the two‑way stopcock an indispensable component in laboratory gas and liquid handling 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 ~ 20mm) for liquid flow control; capillary bore available for precise gas flow regulation
Multiple Configurations: Straight‑bore (standard), oblique‑bore (180° rotation for rapid closure, improved seal), and bent‑outlet (for stopcock bottles and similar applications)

Quality Assurance

Each two‑way stopcock is inspected for taper accuracy, bore 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

Reaction Control

Regulate the addition rate of liquid reagents to control reaction kinetics

Gas/Liquid On/Off Switch

Simple flow control in straight line systems

Vacuum Systems

Independent flow control for multi‑port vacuum manifolds

Apparatus Assembly

Transition component to compensate for angle or position differences

Liquid Dispensing

Bent‑outlet configurations for stopcock bottles and separatory funnels

Compatible Equipment

Standard joint flasks, condensers, separatory funnels, stopcock bottles

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. Two‑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 bore 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

Operation

Open: Rotate the plug to align the bore with both arms
Close: Rotate 90° to misalign the bore with the body wall
For oblique‑bore stopcocks, rotate 180° for rapid closure
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, test seal integrity before use

Cleaning & Storage

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

Two‑Way Stopcock · Selection Guide

Four key dimensions determine the right two‑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 control
Capillary Bore: Precision small‑diameter bore for fine gas flow regulation

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 | High → 12~20mm
③ Media state? Liquid → Straight bore | Gas → Capillary bore
④ Installation location? Standard lines → Straight | High seal → Oblique | Stopcock bottle → Bent outlet

✦ 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 before applying vacuum
Wear protective gloves and safety goggles

Do not

Never use cracked or damaged stopcocks under vacuum or pressure