Extech RF40 Operating Manual

User's Guide

Battery/Coolant Refractometer with ATC

Model RF40

Introduction

Congratulations on the purchase of your RF40
Battery/Coolant Refractometer with automatic temperature
compensation. This precision optical instrument should be
handled gently; avoid touching the optical surface. Careful
use of this instrument will provide years of reliable service.

Description

1. Eyepiece

2. Mirror tube

3. Adjustment Screw

4. Cover plate

5. Prism

Field of View

-60(59%)

-50(56%)

-40(52%)

-30(48%)

-20(44%)

-10(39%)

-5(36%)

+0(33%)

+5(29%)

+10(25%)

+15(21%)

+20(16%)

+25(10%)

ETHYLENE

GLYCOL

F

WATERLINE

1.30

1.25

1.20

1.15

-60(63%)

-50(60%)

-40(57%)

-30(53%)

-20(49%)

-10(44%)

-5(41%)
+0(38%)

+5(34%)

+10(30%)

+15(25%)

+20(19%)

+25(12%)

PROPYLENE

F

GLYCOL

Operation

The instrument measures the refractive index of the sample.

1. Zero Adjustment

Place one or two drops of distilled water on the prism.

Close the cover plate and rotate the adjusting screw so
that the light/dark boundary lines up with the “waterline”.
Once the zero adjustment has been completed, clean the
prism with soft cloth

2. Sample Preparation and Reading

To take a sample reading, simply place a few drops of a
sample liquid on the measurement prism at the end of
the instrument. Lower the cover plate onto the sample
and prism. Open the prism cover and place 2 or 3 drops
on the prism. Close the cover so the liquid spreads
across the entire surface of the prism without air bubbles
or dry spots. Allow the sample to remain on the prism for
approximately 30 seconds.

While holding the instrument under a light source, look
through the
eyepiece. The

Bad

freezing point of the
liquid or the state of
the battery liquid is
determined by the
intersection of the
boundary of the light
and dark fields
(known as the
shadowline) on the
printed scale. If the scale appears out of focus, the
eyepiece may be adjusted by rotating the knurled portion.
The instrument also features an eye guard to prevent
stray light from entering the eyepiece and causing
reflections.

It may be necessary to adjust the position of the light
source to maximize the contrast of the shadowline. Under
normal conditions, optimal contrast is obtained by holding
the instrument underneath and perpendicular to a light
source.

Once a reading has been taken, wipe dry with a clean
cloth (do not wash or rinse) and place the instrument in
the supplied plastic case. Store the instrument in a safe,
dry environment.
Temperature is one of the single most important factors
influencing accurate refractometer readings and is one of
the largest sources of error in measurement.
Temperature compensation relieves the user of the
responsibility to measure temperature and apply a
correction factor when taking readings. This
refractometer makes this correction automatically. When
ambient temperature varies from 68°F (20°C), readings
are automatically adjusted to compensate for
temperature variance between 50°F to 86°F (10°C to
30°C).

Bad Good

Specifications

Range -60 to 32°F for Propylene and
Ethylene glycol freeze point

1.15 to 1.30 specific gravity of battery acid
Resolution 2°F glycol freeze point

0.01 specific gravity of battery acid
Dimensions 6.2x1.6x1.2" (160x40x30mm)
Weight 7.0 oz. (200g)

Calibration and Repair Services

Extech offers complete repair and calibration services for
all of the products we sell. For periodic calibration or repair of
this Extech product, call customer service for details on
services available. Extech recommends that calibration be
performed on an annual basis to ensure calibration integrity.

Warranty

EXTECH INSTRUMENTS CORPORATION warrants this instrument to be free of defects
in parts and workmanship for one year from date of shipment (a six month limited
warranty applies to sensors and cables). If it should become necessary to return the
instrument for service during or beyond the warranty period, contact the Customer
Service Department at [phone] ext. 210 for authorization or visit our website
www.extech.com for contact information. A Return Authorization (RA) number must be
issued before any product is returned to Extech. The sender is responsible for shipping
charges, freight, insurance and proper packaging to prevent damage in transit. This
warranty does not apply to defects resulting from action of the user such as misuse,
improper wiring, operation outside of specification, improper maintenance or repair, or
unauthorized modification. Extech specifically disclaims any implied warranties or
merchantability or fitness for a specific purpose and will not be liable for any direct,
indirect, incidental or consequential damages. Extech's total liability is limit ed to repair or
replacement of the product. The warranty set forth above is inclusive and no other
warranty, whether written or oral, is expressed or implied.

Support line [phone]

Technical support: Extension 200; E-mail: [e-mail]

Repair & Returns: Extension 210; E-mail: [e-mail]

Product specifications subject to change without notice

For the latest version of this User’s Guide, Software updates, and other

up-to-the-minute product information, visit our website: www.extech.com
Extech Instruments Corporation, 285 Bear Hill Rd., Waltham, MA 02451

Copyright © 2009 Extech Instruments Corporation

All rights reserved including the right of reproduction

in whole or in part in any form.

Version 3.0 January 2009

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