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IFPS Upgrades HS Certification

April 1, 2017 0 Articles , 376 Views

Hydraulic Specialist certification manual

Hydraulic Specialist certification manual

The International Fluid Power Society (IFPS) has recently upgraded its Hydraulic Specialist (CFPHS) Certification Study Manual.

Testing for the CFPHS certification starts today, April 1, 2017.

“To keep pace with changing fluid power and motion control technologies, IFPS is committed to reviewing our certification study manuals and tests every five years by a panel of subject matter experts. All material is reviewed for relevance and current technical best practices and standards,” said Donna Pollander, ACA, IFPS executive director. “What the IFPS provides in our newly updated HS study manual and certification test is a highly developed, vendor-neutral, benchmarking tool to evaluate an individual’s fluid power competence, knowledge, and skill set.”

Source: http://fluidpowerjournal.com/2017/03/ifps-upgrades-hydraulic-specialist-certification/

The manual is good, and I like it. But, by my opinion, some stuff has to be changed in this manual:

  1. The font is terrible. I think “Verdana” is not a best choice for study manuals. Standard “serif”-type font like “Times New Roman” is much better for fast reading when there are a lot of sentences in the paragraph.
  2. Text lines are too close to each other. Line spacing in paragraph has to be bigger to easy reading. And I think, it is good idea to use two columns at the page.
  3. Some pictures are raster and in bad resolution. By my opinion, all images have to be in vector format and all photos have to be at least 400 dpi resolution.
  4. Symbols at the schematics are not in accordance with ISO 1219-1. This is a manual for hydraulic certification – you must to follow the standard! (lines type and weight, symbol size, etc.). Schematics made in strange

This is very sad! We pay money for membership, for exams, but IFPS can’t (or doesn’t want) find good specialists to prepare study manual in an acceptable quality!

Proportional valve control calculation. Part 2.

February 20, 2017 0 Articles , , 996 Views

Part 2. Proportional control in the regeneration mode.

Regen mode - proportional control

Fig.1. Regeneration mode schematic

See also:
Part 1. Proportional control of double acting hydraulic cylinder.
Online calculator for cylinder proportional control.

The goal of the calculation is definition of a cylinder velocity at the current operating voltage at the valve’s solenoid.
For calculations we need to know: cylinder and valve parameters (take them from manufacturer catalog), values of forces at cylinder rod (load) and pressure drop at return line (can be assumed as zero if unknown).

Summary:
2.1. Regeneration mode schematic
2.2. Regeneration Mode: Cylinder extension calculation
2.2.1. Balance of forces at the cylinder
2.2.2. Spool lands ratio and pressure drops at the spool lands
2.2.3. Hydraulic cylinder extension. System pressure calculation
2.2.4. Flow through spool lands: max. and at current voltage
2.3. Hydraulic cylinder retraction calculation
2.4. Final words….

Read more >>>

Hose Overall Assembly Length

December 18, 2016 0 Articles 567 Views

There are three different ways to measure hose assembly length are used in the practice:

  1. Use value of “Overall length” (Default for Parker’s suppliers)
  2. Use value of “Seat-to-seat length” (Default for RYCO’s suppliers)
  3. Use value of “Cut length” (Default for EATON suppliers)

 

Unfortunately, there are no any standards for the definition of  “Overall Length” value and therefore different manufactures determine different ways of measuring the value of Overall Length. This is why you need to be very careful before ordering hoses with new supplier and you have to specify which length you provide, because sometimes it can be critical.

The normal practice of “Overall Length” measuring please see below:

All US fittings (JIC, SAE, NPSM), except ORFS fittings, are measured up to the end of the nut:

US fittings

DIN, BSP and ORFS fittings are measured up to the end of the sealing head (this rule does not work with RYCO suppliers, but works with Parker and EATON suppliers):

ORFS fittings

SAE flange fittings are measured up to the face:

SAE flange fittings

All male threads are measured up to the end of the fittings:

male threads

All 90 degree fittings are measured to the head center line:

90* fittings

Other elbow fittings can be measured up to the center line of the head face (RYCO) or up to the center line of the seal face (Parker):

0..90* fittings

I recommend to use Parker’s rule for this type of fittings.

And my last recommendation: check the value of Overall Assembly length: it has not to be less than Minimum Overall ASSY Length:

If the Overall Length is not long enough it could hinder the ability of the hose assembly to function properly. Notes from RYCO:

“This is particularly the case when utilising very short hose assemblies, where a shortening or shrinkage of the hose under pressure may result in hose and coupling separation. In addition, small misalignments, vibration and other displacements may induce very high stresses upon the hose/coupling juncture, as there is little capacity for the flexible nature of the hose to compensate.“

Parameters “A” and “B” you can take from manufacturer’s catalog.

Sources:

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