The fluorescent valve adds phosphor to make it glow in the dark. The darker the light, the more obvious the fluorescent effect.
If you want to make the fluorescent effect more obvious, you can illuminate the fluorescent valve with strong light, so that the fluorescent valve will be brighter in the dark.
If the fluorescent valve does not glow in a dark environment, you can use a flashlight to continuously illuminate the fluorescent valve for 5-10 seconds. The fluorescent valve then glows.
If the valve can not be illuminated, please use a flashlight to illuminate the valve for 5-10 seconds. The valve will glow.