Graduated clogging indicator - operated by adjustable distance from diaphragm contact actuating glow lamps

摘要

A device to indicate a gradual pressure change e.g. the rising negative pressure in a vacuum cleaner as its dust bag becomes full or the clogging of other dust filters, has several differently set indicators side by side each is fitted with a membrane which makes contact at a different negative pressure with a contact for a flow lamp. This gives a more objective and more precise indication than known clogging indicators.