Frequently Asked Questions SLX Submersibles

Contegra Inc Eagan, MN 651-905-0900

Table of Contents

1. How canI test a SLX 130-M in the filed?
2. How do I install a breather system?
3. What makes the SLX 130 and SLX 220 chemically and electrically superior?
4.  
5. What is the temperature performance of the freeze protection sold with the SLX 220 and GPX 220?
6. SLX suspension mounting methods
7. SLX cable run tips
8. SLX product adaptations available
9. Choosing IS barriers for the SLX 100-IS

Back (to FAQs)

How do I install a breather system?

Background:  The Model SLX 100 and the SLX 220 option B are shipped with a separate "breather" enclosure for mounting by the customer in their panel.

Answer:  

1. Prior to mounting the assembly, inspect the breather bag to assure it is inflated approximately to 1/2 its volume.  The bag must be limp to allow it to expand and contract with changes in barometric pressure and temperature.

2. Remove the protective backings from the foam tape on the back of the assembly and adhere the box to the inner panel or (in) side of the enclosure.  Orient the box so the breather hose is at the bottom.

3. Insert the sensor's breather tube into the breather bag's tube.

The breather tube must not be kinked.  Do not bend the signal cable around sharp corners.  Also, do not over tighten the strain relief connector where the signal cable enters the enclosure.

Last edited 12/7/99

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What makes the SLX 130 and SLX 220 chemically and electrically superior?

Chemical resistance:  The wetted parts are of PVC, Viton, Teflon, and PVDF.  These plastics have good chemical resistance in many acids, bases and alcohols.  We suggest you review chemical compatibility charts for your specific application.  The sensor housing is made of PVC and PVDF, the sealing o-rings are of Viton, the diaphragm is PTFE (Teflon), and the cable uses FEP (Teflon).

Electrical transients and lightning "ground bounce":  If a near-by lightning strike elevates the potential of the sensed media, the PVC body and Teflon cable provide a good dielectric barrier.  Additionally, the T420 has three levels of transient suppression on the 4-20 mA loop:  a gas tube arrestor for suppression of high voltages, transorbs, and varistors for fast clamping of lower voltage transients.

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What is the temperature performance of the freeze protection sold with the SLX 220 and GPX 220?

The thermostat turns on at 55 degrees F and off at 85 degrees F. The standard enclosure is uninsulated. The following chart shows the maximum differential temperatures (°F) maintained:

Higher thermostat settings and enclosure insulation are available options.

Last edited 7/5/00

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Cable run tips

Run lengths:  Voltage signals are more susceptible to electrical interference than current loops.  Therefore, it is recommended that submersible sensors with voltage outputs have maximum cable runs of 100 feet.  (700 foot runs have been used successfully.)  4-20 mA loops (for the SLX or GPX) may run for thousands of feet.  Some concerns are:

1. Longer loops have more wire resistance and could require a larger power supply.  Contegra's 18 ga. wire has 5.680 ohms per 1000' of cable, requiring an additional 0.12 volts per 1,000 run.  If a smaller gauge wire is pulled, the resistance will increase and be more of a factor.

2. The signal cable should be run in a separate metal conduit.

Protection:  Secure our cable shield to a good earth ground as near as possible to the transducer.  The T420 has transient protection built-in.  Consult Contegra's sales office to purchase our Transient Protection Module for use on 4-20 mA loops which do not have the protection of the T420 electronics.

Breather tube:  The breather tube must not be kinked.  Do not bend the signal cable around sharp corners.  Also, do not over tighten the strain relief connector where the signal cable enters the enclosure.

Last edited 12/7/99

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Product adaptations available

Cable splice kit:  This kit allows a signal cable to be spliced.  It is waterproof but is intended for the cable run after the transducer's suspension point (due to the suspended weight of the sensor).

3/4" NPT female pressure connection:  The SLX 220 can be adapted to be mounted and sense at a pressure connection in a dry well.  The SLX housing provides waterproof protection for the sensor in the event of flooding.

Last edited 12/16/99

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Choosing IS barriers for the SLX 100-IS

The following list is based upon recommendations by the respective manufacturers.  This is not an exhaustive listing and will be updated.

Transmitter entity parameters:

    Vmax >= Vcc 

    Imax >= Isc 

    Ci + Ccable =< Ca 

    Li + Lcable =< La 

Use the following parameters if the cable parameters are not known:

Cable capacitance = 60 pF/ft.    example: Ccable = 1,000 ft. x 60 pF/ft. = 0.06 uF

Cable inductance = 0.2 uH/ft.     example: Lcable = 1,000 ft. x 0.2 uH/ft. = 0.2 mH

Note: DIN rail isolating standoffs are available for purchase if the INTRINSICALLY SAFE GROUND is not the same as the PANEL GROUND.

Copyright © 2001, 2003  Contegra Inc.   All rights reserved.
Revised: April 19, 2005.