The stand cart features 4 swivel casters that lock and will need to be engaged when not in use.

https://www.amazon.com/PRITEK-Replacement-Industrial-Trailer...
4" Swivel Plate Caster Wheels, PRITEK Heavy Duty Metal Caster Wheels Lock The Top Plate and The Wheels Replacement for Industrial Trailer

so the stand cart is something flat

Ok, the what is the BPV which shall be secured to Stand Cart?


Wenger has new technology for single or twin screw extruders with rotating elements designed to impact more shear and mixing compared to mixing lobes. Homogenizing screw elements improves mixing and is very effective for use in high meat recipes and those high in internal fat.

An adjustable back pressure valve (BPV) has several new features including a third position for relief of die pressure, as well as a reject position and process position. The stem now accepts inserts with round openings and an electric drive is available on the BPV to replace hydraulic drives. The BPV varies extrusion restriction independent of the die, diverts product from the die/knife area during startup or maintenance and allows for adjustments to be made on-line while the system is in operation. The main benefits of BPV are:
https://www.petfoodindustry.com/articles/390-innovations-in-...

Aha. Could you please tell what kind of extruder is that?

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Note added at 8 hrs (2021-01-10 16:29:33 GMT)
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Wenger has integrated three existing process components to provide automatic control of wet bulk density.
Designed to work in conjunction with our Back Pressure Valve (BPV) on the extruder barrel and our integrated APM extrusion control system, the new Wenger Auto Density Control (ADC) automatically measures product density and adjusts the process to maintain the desired density specifications.

https://www.wenger.com/doccenter/6d4b71848a2f45af9dc0fa90817...

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Note added at 8 hrs (2021-01-10 16:42:28 GMT)
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THREE BASIC COMPONENTS
The Wenger ADC consists of three basic components. It can be installed as part of a new system or retrofitted into a system that already has one or more of the basic components. They include:

3 . Wenger’s Back Pressure Valve (BPV) mounted on the end of the extruder to control specific mechanical energy input.

https://www.wenger.com/doccenter/6d4b71848a2f45af9dc0fa90817...

https://www.areopag-spb.ru/obratnye-klapany-dlya-nasosov

The back pressure valve assembly (14) includes an adjustable valve member (48) which can be shifted to alter the effective cross-sectional open area of a product passageway (36), and alternately can be shifted to a product diverting position wherein the product is diverted from downstream processing.

An extruder system comprising:
an elongated tubular extruder barrel presenting an outlet end;
an elongated, axially rotatable, flighted screw within said extruder barrel;
a selectively adjustable back pressure valve assembly operatively coupled to said extruder barrel outlet end, said assembly including a structure defining a passageway with an inlet and an outlet, said inlet communicating with said extruder barrel outlet end, said assembly having an apertured valve member selectively shiftable relative to said passageway for altering the effective cross-sectional open area presented by the passageway; and a product treatment assembly located adjacent said passageway outlet for receiving product after passage through said extruder barrel and back pressure valve assembly, said treatment assembly permitting superatmospheric pressure treatment of said product therein.

https://patents.google.com/patent/US20040043094A1/en