Tip and impact indicators on crates

What each indicator shows

A tip indicator contains a small ball, a marked window or a colour tube that reacts when the crate leans beyond a set angle. Once triggered, the window changes and cannot be reset. A tip indicator works only when the crate is meant to stay upright, since the label is built around that orientation.

An impact indicator, sometimes called a shock label, contains a mechanism that responds to sudden acceleration. A spring-loaded element, a glass tube or a coloured fluid moves past a threshold if the crate is dropped or struck. These are rated by sensitivity, so the label's rating should be chosen to match the load.

Where to fix them

Place indicators on the outside of the crate where a receiver is going to look: the same face as the consignee panel, or the adjacent one, at a height that is easy to read. Put them on a flat, clean panel and not on a joint, a knot or a stencil. The surface should be dry before the adhesive goes on.

Use at least one indicator of each type, and consider a second tip indicator on an adjacent face. If the crate can be received from either end, put a set on both ends. Keep them away from the IPPC stamp and the handling pictograms, which have to stay readable.

Fitting an indicator

Follow the maker's instructions for each label, since mounting details differ between brands. The sequence below covers what is common to most.

1. 01
   Choose the rating

   Pick the sensitivity from the load's fragility. A rugged casting does not need the same label as a calibrated instrument.

2. 02
   Prepare the surface

   Wipe the panel and let it dry. Dust and oil stop the adhesive from holding.

3. 03
   Check the label is untripped

   Read the window before peeling the backing. A tripped label from the box is a reject.

4. 04
   Mount level

   Apply the tip indicator with its arrow pointing up and press firmly across the whole label.

5. 05
   Record the fit

   Photograph the labels in place and note their serial numbers if they have them, so the file shows they were intact when the crate left.

What a tripped indicator means

A tripped label tells you that something happened, and when it was last intact. It does not tell you who handled the crate at that point, or what damage resulted. A receiver should treat a tripped indicator as a reason to inspect, not as proof of damage.

Inspect the crate before opening, then inspect the load. Photograph the label, the crate and any visible damage, and write the observation on the delivery receipt before signing. Notes added later carry less weight with a carrier than notes made at the dock.

What indicators do not do

An indicator is evidence, not protection. It does not stop a crate from being tipped, and a driver who knows a label is on the crate may handle it more carefully, but there is no guarantee. The crate's design, blocking and cushioning protect the load. The indicator records what the crate went through.

Indicators also depend on the load's orientation being correct from the start. A crate loaded on its side by mistake will trip a tip label as soon as it is rolled upright. If a crate is meant to ride in more than one orientation, say so on the quote and the builder will plan the marking accordingly.

Choosing a sensitivity rating

Impact labels come in several sensitivity bands, usually expressed as the shock level that trips them. A label that trips under ordinary dock handling teaches nothing, because every delivery looks abused. A label that never trips on a rugged load is wasted money. Match the band to the load: ask the machine maker how much shock the equipment tolerates, then pick a label tripping slightly below it.

Tip labels have fewer options but similar logic. Some trip when the crate leans past a set angle, and others trip only when it is fully inverted. Pick the one that matches the way the load can be damaged, and note the choice on the crate spec so the next order uses the same label.

Training the people who handle the crate

A label is only useful if somebody looks at it. Tell the warehouse, the driver and the receiving crew that the crate carries indicators, what a tripped one looks like and whom to call. A one-page handling note taped to the crate, or sent with the dispatch, costs nothing and changes how people lift.

At the delivery dock, make the check part of the sign-off routine: read the labels, photograph them, write exceptions on the receipt, and only then move the crate. Receivers who skip the step and open the crate later lose most of the value of the label.