What is The Difference Between Different Types of Gauges for Valve Fittings

Gauges for valve fittings are crucial for ensuring the accuracy and reliability of connections, especially in valves used for containers transporting permanent, liquefied, and dissolved gases. These include applications in breathing apparatus and fire extinguishers. It is important to note that these gauges are not suitable for LPG (liquefied petroleum gas) valves.

In this blog, we will explore the differences between the primary types of gauges used for checking valve fittings: Plug Gauges and Ring Gauges, both plain and thread, which are used to inspect both internal and external threads.

Thread Plug Gauges for Checking Internal Threads

Thread Plug Gauges are primarily used to check internal thread connections. These gauges are typically supplied in sets consisting of three elements:

1. Single-Part Thread Plug Gauge I-2: Used to check the pitch diameter of the thread.
2. Two-Part Thread Plug Gauge for Small End I-4: Used to check the pitch diameter at the small end of the thread.
3. Two-Part Thread Plug Gauge for Large End I-6: Used to check the pitch diameter at the large end of the thread.

These gauges ensure precise measurements of the thread dimensions, confirming that the internal thread meets the required specifications.

Plain Plug Gauges for Checking Internal Threads

Plain Plug Gauges are used for measuring the minor diameters of internal threads. Like the Thread Plug Gauges, they are provided in sets of three elements:

1. Single-Part Plain Plug Gauge I-1: Used to check the minor diameter.
2. Two-Part Plain Plug Gauge for Small End I-3: Used to check the minor diameter at the small end.
3. Two-Part Plain Plug Gauge for Large End I-5: Used to check the minor diameter at the large end.

These gauges are essential for verifying that the internal dimensions of threaded holes are accurate, ensuring proper fitment.

Thread Ring Gauges for Checking External Threads

Thread Ring Gauges are used to check external thread connections. These gauges, like the Thread Plug Gauges, are provided in sets consisting of three gauges:

1. Single-Part Thread Ring Gauge I-8: Used to check the pitch diameter of the external thread.
2. Two-Part Thread Ring Gauge for Small End I-10: Used to check the pitch diameter at the small end of the external thread.
3. Two-Part Thread Ring Gauge for Large End I-12: Used to check the pitch diameter at the large end of the external thread.

Thread Ring Gauges ensure that the external threads are within the required tolerances, providing an accurate fit for the mating parts.

Plain Ring Gauges for Checking External Threads

Plain Ring Gauges are used to check the major diameters of external threads. These gauges come in sets of three:

1. Single-Part Plain Ring Gauge I-7: Used to check the major diameter of the external thread.
2. Two-Part Plain Ring Gauge for Small End I-9: Used to check the major diameter at the small end.
3. Two-Part Plain Ring Gauge for Large End I-11: Used to check the major diameter at the large end.

Plain Ring Gauges play a key role in ensuring that the external threads meet the specified dimensions, ensuring tight and reliable connections.

Key Standards of Valve Fitting`s Gauges

All of these gauges comply with international standards, such as ISO 11363-2018, BS EN ISO 11363-2018, IS 9122-2008, and others like DIN 477 and BS 341-1991. They are designed to fit various sizes and thread types, including 17E and 25E, as specified in these standards.

Choosing the right Valve Fitting gauge for checking thread connections depends on the type of thread and the specific valve fitting requirements. Each type of gauge has a specific function for ensuring precise thread measurements, which are critical in high-pressure systems like gas cylinders, breathing apparatuses, and fire extinguishers.

Depending on the needs and the type of valve fitting, you can select the appropriate Plain or Thread Plug or Ring Gauge for internal or external threads.