1. THE “SANDTRAP”
D O W N H O L E D E S A N D E R
Separates abrasive solids in
production fluids before they
enter a downhole pump.
Extends life of all types of
downhole pumps. Simple to
install and inexpensive.
FEATURES:
• Run on the tubing below any type of downhole pump
• Centrifugal action separates all sizes of solid particles
• Collects solids in extended lengths of mud anchor or in the rathole
• Does not plug or restrict production
• Available for all flow rates
• No moving parts
• All steel construction
• Long life
• Available as a combination “Poor Boy” gas anchor
PATENTED
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2. www.cavinscorp.com
Figure 1 Illustrates the flow path of produced fluids
through the desander sub. Fluid enters the tubing
through the inlet slots. The fluid must flow down through
a spiral to enter the orifice tube and flow upward to the
pump. Centrifugal action, created by the fluids flowing
through the spiral, pushes solids away from the vortex
flow of the orifice tube. Solids settle into the mud anchor
or rathole. The clean fluid flows upward through the
orifice tube to the pump.
Figure 2 Illustrates the position of the desander sub
when used below a rod type pump.
Figure 3 Illustrates the position of the desander sub
and the use of a seal in the casing for ESP applications.

3. DESCRIPTION
The Sandtrap Downhole Desander is run in the tubing below a downhole pump. Production fluids enter the
Desander Sub through its inlet slots. Centrifugal action created within the Desander sub separates solids such as
sand, scale, and iron sulfide from the fluids. The solid particles settle by gravity into the bull-plugged mud anchor
joints or the rathole.
For most reciprocating rod pump applications, the Desander Sub is substituted for a perforated nipple commonly
run below a seating nipple. Instead of running one joint of mud anchor, as many joints as possible should be run
below the Desander Sub. The mud anchor joints must have a bull-plug or a Dump Valve device on the lower end.
A Dump Valve allows the solids within the mud anchor to dump into the rathole on each downstroke of the pump.
The Desander Sub may be elongated in order to perform as a “poor boy” gas anchor.
When using the Downhole Desander below an electrical submersible pump (ESP), an ESP Packer is required.
This system diverts all production fluids into the Desander sub, back into the casing, past the motor for cooling,
and into the pump intake. Solids are collected in extended lengths of bull-plugged mud anchor.
The Downhole Desander may also be used below progressive cavity type pumps. The Desander Sub is run
on the lower end of the pump. As many joints of bull-plugged mud anchor as possible should be run below the
Desander Sub to serve as a sand trap.
Because no two wells are the same, The Cavins Corporation produces several models of the Desander. Please
consult the chart below and contact our sales team, by email at sales@cavinscorp.com and/or phone to an office
location nearest you, to find out which Desander is best suited for your well conditions.
“SANDTRAP” DOWNHOLE DESANDER
MODEL NUMBERS AND FLOW RANGE CHART
FLOW RATE STANDARD COMBINATION
BBL/DAY MODELS GAS ANCHOR & DESANDER
ESP ROD PUMP EUE TUBING SIZE EUE TUBING SIZE
MIN MAX MIN MAX 2-3/8” 2-7/8” 3-1/2” 2-3/8” 2-7/8” 3-1/2”
Less than 75 Less than 35 D230.8 D270.8 D230.8G D270.8G
75 150 35 75 D2301 D2701 D2301G D2701G
100 200 50 100 D2302 D2702 D2302G D2702G
175 350 85 175 D2303 D2703 D2303G D2703G
250 500 125 250 D2305 D2705 D3405 D2305G D2705G D3405G
375 750 185 375 D2307 D2707 D3407 D2307G D2707G D3407G
550 1100 275 550 D2311 D2711 D3411 D2311G D2711G D3411G
800 1600 400 800 D2316 D2716 D3416 D2316G D2716G D3416G
1200 2400 600 1200 FJ2324 D2724 D3424 D2724G D3424G
2400 4000 1200 2000 FJ2340 D2740 D3440 D2740G D3440G
3200 5000 1600 2500 D2750 D3450 D3450G
4000 6000 D2760 D3460
6000 8000 D3480
8000 10000 D34100
* All of the above models may be ordered complete with a funnel to increase separating efficiency of fine solids (i.e.,
fine formation sand, flour/sugary types, iron sulfide, coal fines, etc.).
* For progressive cavity pump (PCP) applications, use the ESP flow ranges.
www.cavinscorp.com

4. CAVINS MDL. ‘MH’ COMBINATION GAS ANCHOR AND
DESANDER
The Cavins Model “MH” Gas Anchor and Desander is equipped with a larger gas
anchor body, which at high flow rates makes it more effective than the Model “G” in
separating out gas before it can enter the downhole pump.
The tool has two body assemblies. The upper body has a larger diameter than
the lower body and serves as the gas anchor. An orifice tube extends downward
through the upper body. The size of the tube may vary in order to maximize gas
separating efficiency. After the gas separates, the fluid enters the desander sub,
which is attached to the bottom of the upper body. There, solids are separated from
the fluid and fall into the mud anchor. Production fluid then flows to the pump.
MDL. ‘MH’ COMB. GAS ANCHORS AND DESANDERS
MODEL NO. TUBING MAX OD
MH3423 2-3/8” EUE 3-1/2”
MH3427 2-7/8” EUE 3-1/2”
MH4427 2-7/8” EUE 4-1/2”
MH4434 3-1/2” EUE 4-1/2”
FLOW TO PUMP
INLET PORTS
BULL PLUG / DUMP VALVE
MUD-ANCHOR
JOINTS
MH GAS ANCHOR BODY
DESANDER BODY
ACCESSORIES FOR DOWNHOLE DESANDER
ESP PACKER ASSY. MUD-ANCHOR DUMP VALVE
MODEL NO. CSG. SIZE TBG. SIZE MODEL NO. TBG. SIZE
CP2344 4-1/2” 2-3/8” EUE DV2375 2-3/8” EUE
CP2354 5-1/2” 2-3/8” EUE DV2875 2-7/8” EUE
CP2754 5-1/2” 2-7/8” EUE DV3400 3-1/2” EUE
CP2770 7” 2-7/8” EUE
CP3470 7” 3-1/2” EUE
CP2775 7-5/8” 2-7/8” EUE
CP2785 8-5/8” 2-7/8” EUE
CP3495 9-5/8” 3-1/2” EUE
THE CAVINS CORPORATION
1800 BERING DR., SUITE 825 – HOUSTON, TX 77057
TEL: (713) 523-9214 -- FAX: (713) 523-9421
WWW.CAVINSCORP.COM