Tank cleaning equipment


General Questions

Tank Specific Questions


If you have a question regarding the performance or operation of any of our products, please feel free to contact us.

Alfa Laval Tank Cleaners General Questions

What is the relationship between Gamajet and Alfa Laval?

Gamajet was acquired by Alfa Laval in 2012. Under the terms of the agreement, a new company was created, Alfa Laval Tank Equipment, Inc. - part of the Alfa Laval Group. This new company is in charge of selling both Alfa Laval Gamajet and Alfa Laval Toftejorg tank cleaning machines. Based in Exton, Pennsylvania, the company name may have changed, but the same "Gamajet" commitment to superior customer service and support will remain the same. Give us a call today and see for yourself!

How does an Alfa Laval tank cleaner work?

As the wash fluid enters our machines, it initially passes through a stationary component called the stator, which directs the water over the veins of a rotating component, called the rotor. The rotor, which is connected to an input shaft, drives a gear train, which ultimately causes the Tee and Nozzle Housings to rotate. The Tee Housing, the piece in the shape of a pipe tee, revolves around the axis of the inlet pipe, while the Nozzle Housing, the piece the nozzles screw into, rotates around the Tee Housing. It is the motion (or more accurately, the relationship of the motion between the two parts) of the Nozzle and Tee Housing which, over time, develop a spherical pattern. One full wash cycle is 60 revolutions of either the Nozzle Housing or Tee Housing. The spray pattern repeats itself after each full cycle.


Two Nozzle Spray Pattern for 4

Quick Rinse/Wash:  Light Rinse/Wash:  Heavy Rinse/Wash:
2 Nozzles  2 Nozzles  2 Nozzles
15 Revolutions  30 Revolutions  60 Revolutions
1/4 Wash Cycle  1/2 Wash Cycle  Full Wash Cycle
12° intervals  9° intervals  3° intervals


Three Nozzle Spray Pattern for 4 

Light Rinse/Wash: Medium Rinse/Wash:  Heavy Rinse/Wash:
3 Nozzles  3 Nozzles  3 Nozzles
20 Revolutions  40 Revolutions  60 Revolutions
1/3 Wash Cycle  2/3 Wash Cycle  Full Wash Cycle
8° intervals  4° intervals  2° intervals

What is impingement cleaning?

Impingement cleaning is a patented process utilized by Alfa Laval tank cleaning machines that projects the cleaning fluid, such as water, in an engineered stream profile that strikes the target surface with precise pressure and angles of impact to provide the most efficient and effective cleaning.

 I am not sure what my operating conditions are, why is that important?

The Alfa Laval tank cleaning machines are wash-fluid driven devices designed to deliver sufficient cleaning force to the vessel surface. The Alfa Laval staff uses the operating conditions such as flow, pressure and temperature to configure the nozzles, the stator (and where appropriate the rotor), and the gear ratio to deliver the required cleaning performance for each application. It is, therefore, very important to know at what pressure and flow rate you plan to operate. Please note, you must take the line and elevation loses into account when sizing a machine. If you require assistance, please contact Alfa Laval.

Which is better, a 2 or 3 nozzle machine?

Each configuration has its advantages.

The two-nozzle machine, which is more common, will generate more impact force than a three-nozzle machine operating at the same pressure and nozzle size. For example, a two-nozzle machine operating at 100 PSI and 100 GPM will deliver 50gpm per nozzle. A three-nozzle machine operating at 100 PSI and 100 GPM will only pass 33 gpm per nozzle this translates into a lower exit velocity, which in turn means lower impact force.

The three-nozzle machine does have a 33% tighter pattern than the two-nozzle. That may sound like a lot, but for most applications, the two-nozzle's pattern is more than enough. There are, however, applications where distance combined with stubborn dirt require the tighter pattern of a three-nozzle machine.

A three-nozzle machine can rinse a vessel in 1/3 of a full cycle, while a two-nozzle machine requires 1/2 a full cycle. Therefore, in applications requiring a very quick rinse, the three-nozzle machine has the edge.

What are Directional Alfa Laval tank cleaning machines?

Directional Alfa Laval tank cleaning machines are machines designed for cleaning open-topped vats, tanks, and other vessels. They use rotary impingement cleaning just like other Alfa Laval tank cleaners, except in this case in a 180° pattern figure instead of the typical 360° pattern figure. The Alfa Laval GJ 4, GJ 5, and GJ 8 are offered as directional units.

What is the difference between an Alfa Laval tank cleaning machine and a spray ball?

A spray ball is a device that has many holes through which the wash fluid is released and it relies on the sheer number of holes to clean the entire surface. However, as a result of the number of holes in a spray ball, the fluid that is released has less force (since the pressure has been diffused) creating a less powerful spray that cleans less effectively. The spray is not only weak but also inexact, unable to guarantee a thorough cleaning. an Alfa Laval tank cleaning machine uses rotary impingement cleaning to ensure that the entire interior of a vessel is cleaned. By using only 2 or 3 nozzles, Alfa Laval tank cleaners ensure the highest impact by concentrating energy into a few very powerful streams. The nozzles are also designed to follow a 360° pattern that cleans the entire surface in one full cycle. The sheer force of water removes the residue while the rotation ensures that no part of the vessel surface goes untouched.

What is the difference between an Alfa Laval tank cleaning machine and a rotary spray ball?

A rotary sprayball does not provide any impingement and relies on a controlled wetting action and chemicals to provide the cleaning. The amount of chemicals required can be substantial. The Alfa Laval tank cleaning unit will also use a fraction of the overall flow rate of a rotary or static sprayball and cleanup to three times faster. In many cases, chemical usage can be severely decreased or eliminated when an Alfa Laval tank cleaning unit is used.

What wash fluids are used with Alfa Laval tank cleaning machines?

Typically water is used, sometimes with a caustic or detergent. In some petroleum applications, diesel will be used. Confirm your wash fluid with the Alfa Laval support team since this will affect the type of seals used in your machine. Solvents are also common. The Alfa Laval tank cleaning machines are made with 316 stainless steel and most cleaning fluids can pass through them without issue, with some severe fluids different o-ring seals and bushings may be required.

How do you size an Alfa Laval tank cleaning machine to work with an existing pump?

To answer this question, one must first determine what type of pump is being used. There are two main families of pumps that work with Alfa Laval tank cleaning machines. The first is a centrifugal or impeller style of pump, the second is a positive displacement pump.

A centrifugal pump moves the wash water with the veins of a rotating impeller. By its nature, as the back pressure in a system builds the pump begins to "slip", i.e. the flow rate drops as the resistance increases. This style of pump can be "dead headed" (zero flow rate) for short periods of time without damage or danger to a properly configured system. an Alfa Laval tank cleaner is typically sized to work close to the centrifugal pump's best efficiency point. This type pump is commonly used in GJ 4, GJ 6, GJ 8, GJ 9, and some GJ 10 applications.

A positive displacement, PD, pump moves the wash water by a more mechanical and constant means (piston, plunger, mechanical diaphragm, etc.). This style of pump is usually rated for a certain maximum flow rate from which it will not vary (but it can be decreased by running the pump slower), and a maximum pressure rating. Do not confuse this maximum rating with the actual operating pressure of the pump. The actual operating pressure is dictated by the restrictions the water must overcome (plumbing, elevation, and Alfa Laval tank cleaning machine) at the set flow rate. Pumps of this style have almost no slip and, therefore, cannot be "dead headed". For obvious safety reasons, a bypass or pressure relief valve must be used on the outlet of constant volume pumps.

One has more freedom when sizing an Alfa Laval tank cleaning machine for use with a PD pump because there isn't a best efficiency point. Using the set flow rate as a guide, Alfa Laval tank cleaners are usually sized to offer the appropriate operating pressure based on factors such as size of the vessel, stubbornness of the dirt, maximum pressure ratings of the pump and supply plumbing, etc. This type of pump is commonly used in the GJ 7, GJ BB, GJ DB and some GJ 5 and 6 applications.

If you have any questions about sizing a pump, please contact us.

What effect do internal vessel obstructions have?

Tanks containing obstructions (baffles, mixing blades, etc.) can have a "shadow" problem. The agitation of the Alfa Laval tank cleaning machine is usually enough to clean around small obstacles, however, for the vessels containing large objects or in applications where high levels of cleanliness are necessary, multiple machines or insertion points are necessary.

What is a full cycle?

As the Alfa Laval tank cleaner rotates inside of a vessel the spray pattern is slowly indexing over the interior surface. When this spray pattern begins to repeat itself, the unit is said to have completed one full cycle. For most machines, this occurs when the Nozzle or Tee Housing has rotated 60 times. The GJ 9, GJ BB and GJ DB require only 50 rotations.

How do I determine an Alfa Laval tank cleaning machine's full cycle time?

Using a fixed point inside of a vessel as a reference, time how long it takes the same nozzle to pass back over that fixed point in vessel. (This will not be the exact same spot because the spray pattern is indexing.) For most machines, this timed value in seconds corresponds to the full cycle time in minutes. For the GJ 9 and  GJ BB and GJ DB multiply this number by 5/6 to calculate the full cycle time (in minutes).

Is it always necessary to run a full cycle to clean my vessel?

No, it is not. If the soil inside of the vessel is light enough, it is entirely possible to use less than a full cycle to clean a vessel. In fact, the spray pattern for a 2 and 3 nozzle machine completes the first pass (not to be confused with cycle) inside of the vessel in 1/2 or 1/3 of a full cycle, respectively. This initial pass is relatively loose in coverage, and in subsequent passes the spray pattern coverage tightens.

What is the maximum practical cleaning radius of the Alfa Laval tank cleaning machines?

See Table below

What is the minimum full cycle time of the Alfa Laval tank cleaning machines?

See Table Below

What are typical flow rates and pressures for the Alfa Laval tank cleaning machines?

See Table Below




Alfa Laval Feature

GJ 7


GJ A6 / GJ 6

GJ 9

GJ 5

Max. Practical Cleaning Radius


.76 m


.76 m


1.5 m


2.3 m


2.3 m

Min Entrance


38 mm

50 mm Bung Hole


71 mm


70 mm

3" Short 76 mm

3½" Long 89 mm

Operating Conditions (Typical)

Flow Rate (GPM)


3 to 6

(11.3 to 22.7)

3.5 to 6

( 13.2 to 22.7)

10 to 25

(37.9 to 94.6)

4 to 30

(15.1 to 113)

10 to 40

(37.9 to 151)

Pressure (PSIG)


100 to 800

(6.9 to 55.2)

600 to 800

(41.4 to 55.2)

30 to 150

(2.07 to 10.4)

200 to 500

(13.8 to 34.5)

100 to 1000

(6.9 to 69)

Full-Cycle Time

3½ to 4½

2½ to 3½

10 to 14

4 to 12

8 to 11




Alfa Laval Feature


GJ 10

GJ 8

GJ 4

Max. Practical Cleaning Radius


3.1 m


10.7 m

25' to 35'

10.7 m


30.5 m

Min Entrance


51 mm

(for Tee Housing)




D-8½" T-7¾" 

216 mm 197 mm

D-4-¾" T-6-¾ (clutch)

121 mm 172 mm

D-12.7/T-11.5 (pin)

323 mm

D-6.7/T-9.6 (clutch)

170 mm

Operating Conditions (Typical)

Flow Rate (GPM)


15 to 20

(56.8 to 75.7)

40 to 80

(151 to 303)

50 to 120

(189 to 454)

80 to 160

(303 to 606)

Pressure (PSIG)


50 to 100

(3.45 to 6.9)

40 to 300

(2.76 to 20.7)

50 to 300

(3.45 to 20.7)

40 to 150

( 2.76 to 10.4)

Full-Cycle Time

10 to 20

8 to 15

8 to 12

10 to 25



I can't rotate the Tee Housing by hand, is this normal?

Yes, it is. Because of the internal gearing the Tee Housing cannot be rotated with normal hand strength, in most machines (except for the clutch machine). Forcing the Housing to rotate will damage internal components.

What types of O-rings are used with Alfa Laval tank cleaning machines?

Most Alfa Laval tank cleaners have Viton® o-rings installed as a standard with common fluids and temperatures. Machines such as the GJ 6, GJ 7 and GJ BB that typically use clean hot water have EPDM o-rings as standard. When solvents are used for the cleaning fluid, Kalrez o-rings are used. If the wash fluid is known, the proper o-rings can be installed.

How important is it to maintain the seals and O-rings of my machine?

Very important. If a machine does not have a regular PM (Preventive Maintenance) program the seals and o-rings, which are wear parts, will ultimately fail and, therefore, cause accelerated wear on the normally non-wear parts.

First, they help control the speed of the machine. The moving parts of the Alfa Laval tank cleaning machine use the resistance of the seals to prevent over-speeding. Also, a leaking machine will have a higher flow rate and less impact if flow is fixed, at a given pressure than a tight one. This greater flow rate translates into a faster machine, and a faster machine translates into accelerated wear on the non-wear parts.

The seals and O-rings prevent the machine from wasting wash water. They ensure that all of the water is used to clean your vessel by forcing it to exit from the nozzles.

How often do I need to maintain the machine?

This depends not only on the type of Alfa Laval tank cleaning machine that you have, but also on the application for which it is used. Your machine’s manual will outline how frequently you ought to maintain the machine.

How do I maintain the machine?

The machine’s manual also describes how to maintain it. Unlike other machines of their kind, Alfa Laval tank cleaners can be maintained using everyday tools that you already have. We also have part kits that you can order for your in-house repairs. However, if you prefer to have someone else take a look at it, our repair program has a 24-48 hour turnaround. You simply send the machine into us and we will disassemble it, clean it, inspect it, and send you a price quote before performing any of the repairs. We then repair and retest the machine at the flow and pressure that it was running at for your application. The cost is $225 for labor plus the cost of any replaced parts.


GJ 4 Questions (for typical operating parameters, refer to table above)

Why does the GJ 4 have two different options for gear ratios (273:1, 675:1)?

The GJ 4 can be used over a wide range of flow rates and for flow rates over 120-130 gpm, the nozzle will spin to quickly to provide proper cleaning. The 655:1 gear ratio allows the machine to use the higher flow rate but still maintain a properly paced rotation and therefore jet dwell time.

What is the difference between a flow-thru and oil unit?

A flow-thru unit uses the wash fluid to lubricate and cool the gear train. An oil lubricated machine has an oil sealed gear train. Oil is a better gear lubricant than water, but over time the oil seals can degrade and food grade oil can exit the unit.

How did the GJ 4 improve on the GJ 3?

The GJ 4 has significant and patented changes from the GJ 3, which include a redesign stem and longer nozzles, which improve fluid flow. The improvements provide more flow and impact at the same pressure. The bell design of the stem shields the unit from debris buildup. Different gear material and pressure angles significantly improved the gear life.


GJ 5 Questions

When do you use a GJ 5 rather than a GJ 9?

The GJ 5 (59:60 bevel teeth ratio) has a tighter cleaning pattern then the GJ 9 (44:45 bevel teeth ratio). A tighter cleaning pattern is useful in larger vessels and some difficult cleaning applications. The Alfa Laval GJ 9 has a smaller profile and can pass through a 3” pipe diameter”


GJ 6 Questions

What is the difference between the GJ 6 and the GJ A6?

The GJ A6 has the same Flo-Thru planetary gear head as the GJ 6, which allows both machines to function without a formal lubricant since the wash fluid cools and lubricates the machines. This is important for applications in the Pharmaceutical, Personal Care, and Food Industries. The GJ A6, however, can be left inside the vessel at all times making it particularly useful for Cleaning Place (CIP) Applications. It also has a polished finish and is self-draining (when installed in a vertical position) and has greater flushing action, all of which add to the sanitary qualities of the GJ 6. However, the GJ A6 leaks more as a result of the greater flushing and lack of seals.

Can the GJ A6 come with a sanitary inlet adaptor?

All machines can use a sanitary inlet adapter. Details need to be provided during ordering to assure proper installation.

Is the GJ A6 FDA approved?

Yes. It uses FDA approved materials.


 GJ 7 Questions

When would you use a GJ 7 rather than a GJ BB?

The GJ 7 is very useful for applications where the machine needs to pass through a 1.5” opening. The GJ 7's smaller size and gear trains have a shorter maintenance cycle than the HD-BB. The GJ BB is more forgiving of rough handling.


GJ 8 Questions

Is the GJ 8 available as a directional machine?

Yes, the GJ 8 is available as a directional machine.

Why was the GJ 8 developed?

The GJ 8 was developed in response to customer the customer request for a lighter and more ergonomic machine with similar flows and impact of the GJ 4.

GJ 9 Questions

Is the GJ 9 that comes with the Cart Klenzr the same as the standard GJ 9?

The GJ 9 in a Cart KlenzR uses a 4 nozzle design to achieve a tighter cleaning pattern in a short cycle. Other than the nozzle the machine is identical.

Can you use a standard GJ 9 with the Cart Klenzr system?

Yes, although the cycle time will be longer


GJ 9.2 Questions

Is the GJ 9.2 only for cleaning fuel tanks?

No, while the GJ 9.2 was originally designed in response to a customer who is cleaning ASTs, the nozzle is used for other applications which require a lower flow, lower pressure nozzle which fits through a 2” opening.


GJ 10 Questions

Can I use the GJ 10 for applications other than UST?

Yes, the GJ 10 is as powerful as the GJ PF but can fit through 4” openings.

Alfa Laval GJ BB Questions

When would you use an GJ BB rather than an GJ 7?

The GJ  BB is a more robust design and has a longer maintenance cycle than the GJ 7 because of the larger gear train. The GJ BB does require more clearance outside the bung.

Alfa Laval Systems Questions

The Portable Restroom System includes a pressure washer. Can I purchase the system without it and use my own pressure washer?

Yes, you can purchase the systems without a pressure washer, but your existing unit must be capable of at least 3.5 GPM.

Does the Cart Klenzr system include a pressure washer?

Yes the system can be sold with or without a pressure washer, but it does require a pressure washer with at least 4 GPM capability.

What operating conditions do the Portable Tank Cleaner and the Blast Station provide for?

Both of these systems are configured for the specific requirements of your application.

What is the difference between the Evacublast and the Gamavac?

The Evacublast has a suction pump and pressure washer. The Gamavac does not provide the pressure washer.

 Does the Evacublast have a heated water option?


Does the Alphajet System come in gas engine or just electric?

The Alphajet system can be provided with an electric engine.

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