Seiko & Citizen Watch Forum Message Archive

Dear Sir and Madam:

My name is Ikuo Tokunaga. I am an engineer of SEIKO and I have developed a lot of special watches such as deep-sea diver's watches, pilot watches, adventure watches, railway watches and so on over a span of thirty years.

At the same time, I have been a member of the technical group and ISO working group of the Japan Clock & Watch Association for a long time, and now I am the chairman of the ISO(International Organization for Standardization ) working group.

It is a great honor for me to have this opportunity to talk to you in this forum of wonderful site of timepieces.

I would like to talk with you about the wonderful world of timepieces through this site.

Since the international work about the ISO is my main work and very busy now. Therefor the work of my site http://www.tokunaga.ne.jp is left to my dependable son Tacky.

Tacky found a question in this forum on the other day during my overseas business trip.

The question was concerning the formula of Q=K(P1-P2)at/l.

This formula expresses Q=the quantity of the gas or water which penetrates into the inside of the case. K is the penetration coefficient of the gas or water which is decided by the material of the gasket. P1 is the pressure of the outside of the case. P2 is that of the inside of the case. a is the cross-section area of the gasket. t is time. And l is the length of the water-sealing portion of the gasket.

This formula is used in order to calculate the quantity of He-gas or water which penetrates and goes into the inside of the case on the design of diver's watch.

I would like to conclude my description by hoping that you will use our SEIKO watches with love forever.

I thank you very much for reading my message.

Sincerely yours,

Ikuo Tokunaga