Vogelsang XRipper twin-shaft grinder

The XRipper exists because of what people flush. Wet wipes, sanitary items and textiles bind into rag, rag wraps an impeller or bridges a valve, and a pumping station that used to run itself starts generating callouts. The XRipper is Vogelsang's answer to that: a twin-shaft shredder that sits in the flow, catches the material and cuts it down to a size the plant behind it can pass. Vogelsang also puts it on entangled material coming back out of digesters, and on bones, fruit, vegetables and food-production waste on the industrial side.

It is a grinder, not a pump and not a screen. It adds nothing to the flow and takes nothing out of it. Everything that goes in comes out the other side, smaller. Get that straight before you look at the model list, because it decides whether the machine is any use to you.

Which series

Four of them, and the installation picks it more often than the duty does.

The XRS is the horizontal inline unit and the cheapest way into the range: grey cast iron chamber, Ø100 mm to Ø200 mm flanges, 50 to 325 m³/h. The XRP does the same job with the motor stacked vertically above the rotors, which is what you specify when the machine has to go into a shaft with no floor space. It starts at 406 mm flange to flange and runs to 1,140 m³/h. The XRC-SIK is for open channels. It hangs on a Sewer Integration Kit rail system so a crane can lift the whole machine out of the channel for service, and it takes inlet openings from 219 × 320 mm up to 500 × 1,300 mm. The XRG is the large-flow machine, with sieve drums either side of the rotors that let water past while holding the rubbish back and feeding it in continuously. That is what gets it to 7,164 m³/h in a 1,370 mm wide frame.

Read the throughput figures properly

Every throughput number Vogelsang publishes for the XRipper is a maximum theoretical figure for water, at a stated pressure loss: 0.25 bar for the XRS, 0.15 bar for the XRP. The channel machines are quoted at optimum sewer conditions. Sewage carrying the rag you bought the machine for will not behave like water, and the useful figure is the one that comes out of Vogelsang's sizing software against your channel or your pipe. Treat the table figures as ceilings, the way you would read the end of a performance curve.

What it costs you

A machine you did not have before, in a line that previously had nothing in it. The Ripper rotors and the axial wear plates are consumables, and on a works where the grit removal is not doing its job they will go faster than the brochure life. Rotors can be turned 180 degrees and run the other way round, which buys you a second life out of the same part, but they are still a wear item to budget at specification rather than at the first service.

There is a second cost that gets missed. Grinding does not remove anything. If your consent or your process needs the rag off site, you want screening and a skip, because the XRipper will pass a finer version of the same material straight into the works. It earns its place where the problem is mechanical damage and blockage downstream, not where the problem is solids load.

Where it is the wrong machine

If the medium is a process liquid that must leave at a controlled particle size, or if stones and metal are getting in, look at the Vogelsang RotaCut instead. It cuts against a perforated screen, so the hole pattern fixes the free passage, and every machine carries a heavy material separator as standard. The XRipper has no screen and separates nothing by default; a connector box can be added ahead of the XRS and the XRP to drop stones and metal out, but on the XRC and XRG that option is not on the list.

And the honest one: check the pump first. The mistake we see most often on a blocking station is a pump swapped like for like, when the pump was never the fault. A grinder is a system change and it fixes a system problem. If nothing is actually failing downstream, an XRipper is a drive, a gearbox and a set of wear parts you have volunteered to maintain.

Solids arrive with the flow and are guided into the centre of the housing, where the two Ripper rotors intermesh. Water passes the rotors more or less unhindered, because the housing is deliberately oversized and the pressure loss across it is small. Solid matter is ripped, long fibre is cut by the sharp edges, and coarse brittle material is ground. The size the material leaves at is set by the width and contour of the Ripper blades, not by a screen.

Two details do most of the work. The axial wear plates carry a counter-cutter, which is what stops disruptive matter slipping past the rotors unshredded. And the two shafts turn at different speeds, so anything that settles into the gaps between the rotors gets raked out as the rotors pass each other. That is the self-cleaning action, and it is why the machine resists ragging rather than collecting it.

The rotors themselves are cut from a single block of steel on CNC machines: a high-strength core, narrow gaps, hardened cutting edges. Because the drive torque is carried by the rotor body rather than through a carrier shaft and a stack of discs, the assembly is stiff enough not to need intermediate bearings. Shafts and rotors are dimensioned to the largest diameters that will fit, which is what makes the unit torsionally stiff and hard to stall.

The XRipper XRS, inline in cast iron

The XRipper XRP, inline with the motor above

Note the direction of travel in that last column. The biggest inline XRippers are the lowest pressure rated: 8 bar on the small frames, 4 bar by the time you reach the 186 series. If the machine is going on the discharge side of a pump, the pressure at that point decides the frame before the flow does.

The XRipper XRC-SIK, for open channels and shafts

The XRipper XRG, for high flow

On the XRG the rotors and the High Capacity Units are driven independently, so each can be geared to its own job and each can be monitored on its own. If one stalls you know which one, and the other keeps working.

Materials, options and the drive

The chamber is grey cast iron on the XRS and steel on the other three series, with stainless steel and cast stainless steel available. Ripper rotors and axial wear plates are a highly wear-resistant special steel as standard, and a stainless variant is offered for chemically aggressive media. Flow-optimised housings are an option on the XRP and the XRC.

For long rotor sets, or where hard blockages are expected, the QD design adds a third support bearing. That stops the shafts deflecting far enough for the rotors to touch each other, which is the failure the length would otherwise buy you. Every QD machine keeps the same on-site serviceability as the rest of the range.

Drive is normally a geared motor or a parallel shaft geared motor, rated IP55 on the XRP and XRC. Versions suitable for temporarily or permanently flooded operation are available, and the XRipper can be driven hydraulically instead. Vogelsang can supply an ATEX-compliant version for equipment going into a hazardous area; specify the zone when you enquire, because that decides the drive and the certification the manufacturer has to issue against it.

What it looks like in service

Vogelsang publishes a case study at the Nigg wastewater treatment works in Aberdeen, a 250,000 population equivalent site run by Scottish Water, where an XRC186-520QD SIK replaced twin-shaft grinders that had to go off site for overhaul. Vogelsang reports a 60% reduction in maintenance cost over the first 12 months against the units it replaced, with the servicing done by the plant's own engineers. That figure is the manufacturer's, not ours. The mechanism behind it is the part to take away. On the XRP, XRC and XRG the whole functional unit lifts out in one piece, motor, gearbox, shafts and rotors together, while the housing stays bolted where it is. On the XRS the cover comes off and the wear parts follow it. Nothing has to leave the works, which is where the cost of a grinder overhaul normally goes.