The International Organization for Standardization (ISO) is a worldwide federation of national standards bodies.

This organization has produced a standard (ISO 484/2) that defines the manufacturing tolerances for marine propellers.

ISO 484 Accuracy Classes

Class

Description

S	Very High Accuracy

I	High Accuracy

II	Medium Accuracy

III	Wide Tolerances

ISO Tolerances on Pitch

Class			S	I	II	III
a)	Local Pitch	Pitch of one portion of one blade	± 1.5%	± 2%	± 3%	-
b)	Section Pitch	Mean pitch of one radii of one blade	± 1%	± 1.5%	± 2%	± 5%
c)	Blade Pitch	Mean pitch of one blade	± 0.75%	± 1%	± 1.5%	± 4%
d)	Propeller Pitch	Mean pitch of all blades	± 0.5%	± 0.75%	± 1%	± 3%

The users of Prop Scan have found the ISO 484 standards a very fair method of propeller inspection.

Due to the Prop Scan measuring concept and advances in computer technology we have been able to enhance the ISO 484/2 specifications.

Prop Scan EPS (Enhanced Propeller Standards)

EPS - Enhanced Propeller Standard

Prop Scan EPS - (Enhanced Propeller Standard) is used in the correction and modification of propellers and has been developed by experts in the field to further enhance the well respected ISO 484 Standard.

Prop Scan EPS can measure propellers down to a 2" diameter.

In addition to local pitch measurements, Prop Scan EPS measures the complete pressure face and presents a tolerance band to control the face contour.

Prop Scan EPS adds an additional accuracy class (displayed in light blue).

Class

Description

Prop Scan EPS Class

O	Extremely High Accuracy

ISO 484 Classes

S	Very High Accuracy

I	High Accuracy

II	Medium Accuracy

III

Wide Tolerances

ISO and Enhanced Tolerances on Pitch

Class			0	S	I	II	III
a)	Local Pitch	Pitch of one portion of one blade	± .75%	± 1.5%	± 2%	± 3%	-
b)	Section Pitch	Mean pitch of one radii of one blade	± .5%	± 1%	± 1.5%	± 2%	± 5%
c)	Blade Pitch	Mean pitch of one blade	± .38%	± 0.75%	± 1%	± 1.5%	± 4%
d)	Propeller Pitch	Mean pitch of all blades	± .25%	± 0.5%	± 0.75%	± 1%	± 3%

Prop Scan EPS Features

A propeller is measured each degree of rotation on the pressure face resulting in the total section Face Camber being scanned. The following table displays the Prop Scan EPS Face Camber advantages.

Prop Scan EPS compared to ISO 484/2
	EPS Face Camber		ISO 484/2 Face Scan
Class	Measurements	Local Pitch	Measurements	Local Pitch
0	57	4	NiL	NiL
S	57	4	5	4
1	57	3	4	3
2	57	2	3	2
3	57	2	2	-
The average propeller is approximately 57 degrees from leading to trailing edge

Prop Scan EPS takes 57 precise ‘looks’ (recorded measurements) at each measured section of a propeller for all ISO 484/2 Classes. These are in addition to the regulation ISO 484/2 Local Pitch measurements.

The ‘uncharted’ areas between the measurement points (5 for ISO 484/2 Class S) are now ‘looked at’, enabling problems in these areas to be corrected. This precision is in excess of the precision required for Navy propellers. Prop Scan EPS was developed for Navy repair contracts.