Summary of the most frequently asked questions & answers about X-ray tubes and service issues.

1. My X-ray system is down - where can I get support?

Please contact your local service agent of the equipment manufacturer.

COMET's business model is centered on Original Equipment Manufacturers (OEM). We do not supply or service our products at end-users. If you need assistance, we can help you to find an appropriate service company in your region.

2. What is the difference between the focal spot standards IEC 336 and EN 12543?

EN 12543 (Non-destructive testing – Characteristics of focal spots in industrial x-ray systems for use in non-destructive testing – Pinhole camera radiographic method) has replaced the IEC 336 standard (X-ray tube assemblies for medical diagnosis: Characteristics of focal spots). There is no clear geometrical formula for converting one size to the other because the measurement method was different. For a conversion of the focal spot sizes of COMET tubes, please refer to the table below:
IEC336 Focal Spot Size EN 12543 Focal Spot Size
0.06 0.2 mm
0.2 0.5 mm
0.3 0.75 mm
0.4 1.0 mm
0.5 1.3 mm
0.6 1.5 mm
0.8 1.9 mm
1.0 2.3 mm
1.2 2.5 mm
1.5 3.0 mm
1.8 3.6 mm
2.0 4.0 mm
3.0 5.5 mm
3.2 5.8 mm
4.0 7.0 mm
4.5 7.5 mm
5.0 8.0 mm


3. How long does an X-ray tube last, and what does its life span depend on?

The limiting factor of an x-ray tube under normal operation is its heating coil (filament). Its expected service life – limited by the vaporization of the tungsten –is indirectly proportional to the filament current. The function, however, is a logarithmic one.

Technically speaking, x-ray tube life is not easy to predict because it depends greatly on the application circumstances.

We have seen tubes still running after 15 years, which had accumulated only a few hundred hours of operation, for example in radiographic applications or research facilities.

On the other hand, tubes can be worn out after 3 years when operated on a 24/7 basis (such as in security equipment or in-line inspection systems in casting production).

The typical tube life should be somewhere between 3 and 5 years, or 10,000 to 30,000 hours.

From an investment point of view, the tube itself (and HV cable) should be amortized within 2 years as it can be regarded as a consumable item (like a light bulb).

The HV generator and lead cabinet can be amortized within 10 years, as they are regular, non-consumable equipment.