Types of Machine Guards – There are several different types of machine guards, Guards are materials that keep workers from having direct contact with moving parts and other dangerous areas of a machine. Some guards also protect workers from shavings, flying shards or metal sparks created by working machines.
Fixed guards Interlocking guards Adjustable guards Self-adjusting guards
Contents
How many types of guards are there?
There are four general types of guards: Fixed. Interlocked. Adjustable.
What are examples of guarding?
- By Standard Number
- 1910.212 – General requirements for all machines.
- Part Number: 1910
- Part Number Title: Occupational Safety and Health Standards
- Subpart: 1910 Subpart O
- Subpart Title: Machinery and Machine Guarding
- Standard Number:
- Title: General requirements for all machines.
- GPO Source:
1910.212(a)(1) Types of guarding. One or more methods of machine guarding shall be provided to protect the operator and other employees in the machine area from hazards such as those created by point of operation, ingoing nip points, rotating parts, flying chips and sparks.
Examples of guarding methods are – barrier guards, two-hand tripping devices, electronic safety devices, etc.1910.212(a)(2) General requirements for machine guards. Guards shall be affixed to the machine where possible and secured elsewhere if for any reason attachment to the machine is not possible.
The guard shall be such that it does not offer an accident hazard in itself.1910.212(a)(3)(i) Point of operation is the area on a machine where work is actually performed upon the material being processed.1910.212(a)(3)(ii) The point of operation of machines whose operation exposes an employee to injury, shall be guarded.
The guarding device shall be in conformity with any appropriate standards therefor, or, in the absence of applicable specific standards, shall be so designed and constructed as to prevent the operator from having any part of his body in the danger zone during the operating cycle.1910.212(a)(3)(iii) Special handtools for placing and removing material shall be such as to permit easy handling of material without the operator placing a hand in the danger zone.
Such tools shall not be in lieu of other guarding required by this section, but can only be used to supplement protection provided.1910.212(a)(3)(iv) The following are some of the machines which usually require point of operation guarding: 1910.212(a)(3)(iv)(a) Guillotine cutters.1910.212(a)(3)(iv)(b) Shears.1910.212(a)(3)(iv)(c) Alligator shears.1910.212(a)(3)(iv)(d) Power presses.1910.212(a)(3)(iv)(f) Power saws.1910.212(a)(3)(iv)(g) Jointers.1910.212(a)(4) Barrels, containers, and drums.
Revolving drums, barrels, and containers shall be guarded by an enclosure which is interlocked with the drive mechanism, so that the barrel, drum, or container cannot revolve unless the guard enclosure is in place.1910.212(a)(5) Exposure of blades. When the periphery of the blades of a fan is less than seven (7) feet above the floor or working level, the blades shall be guarded.
The guard shall have openings no larger than one-half (½) inch.1910.212(b) Anchoring fixed machinery, Machines designed for a fixed location shall be securely anchored to prevent walking or moving.
What is an automatic guard?
Automatic guards – Automatic Guard Automatic guards will ensure that the operator is prevented from coming into contact with dangerous parts when the machine is set in motion accidentally. This guard is itself actuated by the movement of the dangerous part. It can only be used where sufficient time is available to remove the body part from the danger zone viz.
What are the different types of interlock guards?
Cascading conveyor system – Another example of a logical interlock is a cascading conveyor system. Simply put, the upstream conveyors are waiting for the downstream conveyors to start, and remain clear, to allow for boxes to move downstream. This means we first need to start motor 3. This means that the open contacts of motor 3 and motor 2 work as an interlock for motor 1 and the open contact of motor 3 works as an interlock for motor 2. If there were not any interlocks on the conveyors then the running conveyors would jam the boxes regardless of whether the downstream conveyor was running or not. In summary, an interlock is a method for restricting action. There are two main types of interlocks: – sa fe – no n-safe. There are three types of interlocks: – mechanical, – electrical, – logical. Each interlock has a specific use to help take control of a system and prevent undesirable actions.
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What do you call the person you are guarding?
Defender. noun. someone who supports something or who works to prevent it from being lost or taken away.
What does guarding mean in safety?
What is safeguarding? – Back to top The CSA standard Z432 Safeguarding of machinery defines safeguarding as: ” protective measures consisting of the use of specific technical means, called safeguards (guards, protective-devices), to protect workers from hazards that cannot be reasonably removed or sufficiently limited by design.” Note: This OSH Answers fact sheet is based on CSA standard Z432-16 Safeguarding of machinery.
What is a barrier guard?
Presses » Barrier Guards – Barrier Guards are appropriate safeguards for full revolution and part revolution mechanical power presses. They are designed to keep the operator’s hands and arms from entering the “danger zone” as prescribed by the particular machine. Barrier guards are usually the first point-of-operation safeguard considered for machines.
Why is it called guard?
Early 15c., ‘one who keeps watch, a body of soldiers,’ also ‘care, custody, guardianship,’ and the name of a part of a piece of armor, from French garde ‘guardian, warden, keeper; watching, keeping, custody,’ from Old French garder ‘to keep, maintain, preserve, protect’ (see guard (v.)).
What is a trip guard?
What is Fixed Interlocked Automatic & Trip (FIAT)? – Definition from Safeopedia Fixed, automatic, interlock and trip are different methods of machine safe guarding. Guards are barriers which prevent access to danger areas. The appropriate safeguarding method for a particular machine will be determined by the type of operation, the size and shape of the stock, the layout of the work area, and the production requirements and limitations.
Guard design needs to ensure that there is no interference with visibility. A fixed guard is a permanent part of the machine and is not dependent on other moving parts to perform it’s function. An interlocking guard utilizes a tripping device, which automatically powers off the machine when it is triggered.
Adjustable guards allow the user flexibility to adjust the guard in accord with the size of stock. A trip guard has barriers that automatically open and close in accord with the movement of stock. Synonyms Machine Guarding, Safety Manual, Machine Safeguarding, Guarding Share this Term : What is Fixed Interlocked Automatic & Trip (FIAT)? – Definition from Safeopedia
What are guard functions?
Security Guard job profile – To write an effective Security Guard job description, you need to understand what exactly a Security Guard does. Security Guards duties often include securing premises and personnel by patrolling property, monitoring surveillance equipment and inspecting buildings and equipment. Security Guards duties can also access points as well as permitting or prohibiting entry.
What is a movable guard?
Movable guards are a basic measure used to keep operators and other personnel at a safe distance from these parts and to prevent people coming into contact with them.
What is a guard locking system?
Assessment of the Safety System on a Door with Guard Locking The use of guard locking on safety doors has long been a proven technology for protecting machines with overtraveling movements. Guard locking ensures that the safety door cannot be opened until the machine has come to a complete stop.
- Assessing this type of safety system is anything but simple according to the currently valid standard.
- The successor standard promises clear improvements here.
- The new EN ISO 14119 standard The currently valid EN 1088 will soon be superseded by EN ISO 14119.
- Both standards provide assistance in the assessment of interlocking devices on movable safety guards.
In addition to EN ISO 14119, all other valid standards taken into account for assessing the “guard locking” safety function will be introduced briefly below. The “main standard” in connection with safety doors is currently EN 1088, “Safety of machinery – Interlocking devices associated with guards – Principles for design and selection”.
This standard has existed since 1995 and was most recently supplemented and published in 2005. The date of the standard is now 2008, but only legal adaptations to the modified Machinery Directive have been added. In terms of content, virtually nothing has changed since the initial publication. A fundamental revision of EN 1088 has been in progress for several years.
The draft appeared in the year 2011 under a new number – prEN ISO 14119. The final version is scheduled to appear in early 2013. It has again undergone extensive revisions compared to the draft version. Several key changes will be introduced briefly over the course of this article.
- Standard assessment of guard locking using a lathe as an example The path through the standards is to be described completely one time based on a simple example.
- A lathe, whose main hazard is the rotating main spindle with the clamped workpiece, serves as the example.
- In the first step, the risk analysis can be performed according to EN ISO 12100, or according to the respective C standard, EN ISO 23125, for lathes.
The analysis reveals that a cover over the hazard area is necessary due to the possibility of parts being thrown out of the machine. It then must be assessed whether an interlocking device on the protective cover suffices or whether a guard locking device must be used here.
- The standard used for assessment is EN ISO 13855.
- This standard regulates the calculation of the distance of safety doors from a hazard area.
- Section 9 of this standard describes the required minimum distance for a safety device so that no hazard can occur after the door is opened during an overtraveling movement.
Alternatively, if the distance is not observed, guard locking can be used. It, in turn, must then be selected according to EN 1088, or soon according EN ISO 14119. According to EN ISO 13855, the minimum distance of the safety guard from the hazard area is calculated using the formula S = K * T + C.
- S is the minimum distance, K is the approach speed, T is the time until the machine has been put into a safe state (overtravel) and C is the minimum constant to be observed according to the openings in the safety guard so that no hazard area can be reached in a running machine.
- For our example involving the lathe, the result is that the value 0 can be assumed because the protective cover does not have any openings.
The distance from the workpiece to the intended protective cover is 200 mm. With this value, the resulting maximum permissible overtravel time is 0.125 s (K = 1,600 mm/s as constant from the standard), which can be extended by a value required open the cover.
- This value is assumed to be 0.5 s by the designer of our lathe.
- Therefore, the maximum permissible overtravel time is 0.625 s.
- The drive in our example does not meet this value; it does not stop until approx.1 s has elapsed.
- Therefore, either the distance must be increased or guard locking must be used.
In our example, guard locking is used that must meet the requirements of EN 1088 and, beginning with the validity of EN ISO 14119, the requirements of this new standard. A key requirement in both standards is that guard locking must be unlocked by energy and locked by spring force (closed-circuit current principle).
- Only in justified exceptions is it possible to use a different principle.
- One possible reason for an exception is, for example, that a fire could start in an installation and access to a machine must be ensured for the fire department even in the event of power failure.
- Another possibility intended in EN ISO 14119 for gaining access to the machine in emergency situations is emergency unlocking.
This allows the guard locking device to be unlocked without tools in the event of danger. For the lathe example, safety switch STP3 from EUCHNER, which meets the above requirements according to the closed-circuit principle from EN ISO 14119, is suitable for guard locking.
- The STP is an electromechanical safety switch with guard locking and guard lock monitoring.
- Its slim design permits simple and space-saving installation.
- The fiber glass reinforced plastic housing and the high degree of protection (IP67) permit use in very harsh environments.
- The metal head permits realization of guard locking forces up to 2,500 N.
In this application, a switching element with four positively driven NC contacts is installed. Two of them are used for door monitoring and two for solenoid monitoring. The next requirement, which was adopted unchanged in EN ISO 14119, states that the locked position of the guard locking device must be monitored so that the machine can be put into operation only if the guard locking device is actually closed.
The associated safety function is monitoring of the locking mechanism of the guard locking device. This must be realized according to the risk analysis. Category 3 according to EN ISO 13849-1 must be achieved in our example, because the required PLr is d. For the selected STP3, contacts 11 – 12 and 31 – 32 are used for this purpose.
They both monitor the position of the guard locking solenoid pin. The technical realization of the safety function is to be assessed in the next step. EN ISO 13849, for example, can be used for this purpose. Several questions arise when guard locking is assessed according to EN ISO 13849-1.
- Electronic monitoring is usually realized with two channels, such as described in our example above.
- However, Categories 3 and 4 clearly demand two sensors.
- Does this mean that two guard locking devices must be used as well? EN ISO 14119 answers this question by stating that fault exclusion on breaking of guard locking is also permissible for PL e or SIL 3.
In other words, only one guard locking pin has to be used. It is therefore sufficient to use only one STP3 as the guard locking device. The diagnostic coverage DC is determined in the next step. For this purpose, the circuit must be designed to detect as many faults as possible.
One solution here would be to integrate a second sensor as a door position signal, for example. With the aid of this sensor, it is then possible, depending on evaluation, to find the faults and thereby also to achieve the required diagnostic coverage DC. Alternatively, it is still possible to perform fault exclusion on parts of the safety chain.
In this case, the second sensor would not always be necessary. The procedure for fault exclusion is described in the overview “Proven Systems – Proven Safe” from Euchner. Another question after the safety assessment is the control of a guard locking function.
- Is this relevant for safety and, if yes, how is assessment performed in this case? The new EN ISO 14119 also answers this question, but unfortunately not quite unequivocally.
- In a comment, it states that the Performance Level PL is typically lower than the PL of the guard locking position monitoring.
This is because a hazard due to failure exists only briefly in most cases. The reason is that the monitoring circuit for the locked position switches the machine off as soon as control of guard locking incorrectly opens the safety guard. Therefore, the hazard posed by an overtraveling machine exists exactly once in most cases.
- Ultimately, the result certainly will be single-channel control in most practical cases.
- This must satisfy the demands of PLr from the risk assessment.
- By the way, a guard locking device typically includes another safety function: prevention of unexpected start-up of a machine.
- Since the same components as for guard locking of the safety guard are used for this purpose in most cases, the safety assessment can be adopted from the guard lock monitoring function.
This is based on the fact that guard locking devices, e.g. as with safety switch STP, have always included a so-called failsafe locking mechanism. Failsafe locking means that a mechanism prevents the guard locking device from locking without the safety guard being in closed position.
- For this function, the STP3 includes additional contacts for monitoring the position of the safety guard.
- A guard locking device thus fulfills very many functions at once.
- According to EN ISO 13849-1, it is now necessary to produce a block diagram from the electric circuit based on the structure of the selected category.
This not very simple, especially for guard locking devices. The “SISTEMA Cookbooks” from the German Social Accident Insurance (DGUV) provide good instructions for creating the diagram. Additional resources on this topic will appear in future. In connection with EN ISO 13849, the assessment of a series connection of electromechanical safety switches is also interesting.
Whereas the draft of the new standard, prEN ISO 14119, still included assistance on this topic, this material will be omitted in the final version. At the same time, a paper will appear to explain this topic better and more comprehensively. An appendix of a standard cannot address such a complex topic in sufficient detail.
With the future EN ISO 14119, the assessment and use of the proven electromagnetic guard locking devices will be significantly easier overall, because the procedure is described more clearly. Moreover, the new standard includes a simplified assessment of the tampering hazard and a description for the connection to a control system.
- However, these are only a few of the changes included in EN ISO 14119.
- Modern safety solutions simplify assessment Modern solutions for guard locking devices, such as the Multifunctional Gate Box MGB (system for protecting safety doors) or the CET (transponder-based safety switch with mechanical guard locking) from Euchner, already represent a complete subsystem according to EN ISO 13849-1, because evaluation of the safety signals is already integrated into the device.
Consequently, the required block diagram can be produced even more simply. Calculation of the characteristic safety values is simpler, because they can already be provided by EUCHNER. Series connection is also possible with this type of guard locking devices without reducing the PL of the overall circuit.
What is the difference between interlocking guards and automatic guards?
Warren Forensics In the three-part series on the CE mark, we scratched the surface of some of the requirements an equipment manufacturer must meet in order to earn this designation. of the series dealt with some of the requirements for the design of a guard.
- One of the items for consideration with the design of a guard is the frequency that someone will need to access the area protected by the guard.
- If access is needed on a routine basis, often defined as more than once per shift, the guard needs to be designed to be movable instead of fixed.
- Movable is defined as able to be opened without the use of tools.
Otherwise the frustration and time requirements of obtaining tools and removing a fixed guard will often lead to the guard being discarded. However, once you make the guard movable, how do you ensure that the guard is in place when it needs to be? The answer is an interlocking guard.
- The first sentence in the Scope section of the standard reads:
- “This International Standard specifies general requirements for the design and construction of guards provided primarily to protect persons from mechanical hazards.”
- ISO 14120 defines the term “interlocking guard” in the following way:
- “guard associated with an interlocking device so that: -the hazardous machine functions ‘covered’ by the guard cannot operate until the guard is closed;
- -if the guard is opened while hazardous machine functions are operating, a stop instruction is given; -when the guard is closed, the hazardous machine functions ‘covered’ by the guard can operate, but the closure of the guard does not by itself initiate their operation”
Washing machine with open and closed door. So, what is an interlocking guard, have you ever thought about it? A perfect example is the lid on your clothes washing machine. In the very early days of the washing machine, the drum of a washing machine was not even covered with a lid creating a dangerous condition in the form of motion hazards.
A guard was added over time to address this hazard in the form of an enclosure with a lid, but the machine would still operate with the lid open. Further improvements to the guard led to the addition of a lid switch, which is an interlock, to prevent the drum from spinning when the lid was open. These could often be defeated with a simple paperclip or fingertip by curious people, like young boys who like to see how things work! The new washing machine we have at home features not only an interlock to prevent the spin cycle from happening when the lid is open, but also a locking feature to prevent the lid from being opened while the drum is still in motion.
This is actually an “interlock with guard locking”, as defined by ISO 14120 Section 3.6 below:
- “interlocking guard with guard locking
- guard associated with an interlocking device and a guard locking device so that:
- -hazardous machine functions “covered” by the guard cannot operate until the guard is closed and locked;
- -the guard remains closed and locked until the risk of injury from the hazardous machine functions has passed;
- -when the guard is closed and locked; the hazardous machine function “covered” by the guard can operate, but the closure and locking of the guard do not by themselves initiate their operation.”
The crucial difference between the two is that the interlocking guard will not allow the machine to operate unless the guard in place but will still allow the guard to be moved or opened without the machine being in a safe, stopped position. An interlocking guard with guard locking will not allow you to open or move the guard until the hazardous motion has stopped.
Which one is right for your design? The risk assessment, discussed in of the CE blog, comes into play in this selection. The hazard must be assessed and fully understood. The hazards associated with a rotating drum in a washing machine at full speed cannot be instantly made safe. It takes some time for the drum to wind down to a dead stop and eliminate the hazards of motion, hence the interlocking guard with guard locking to keep the lid shut until the drum stops.
However, some hazards can be made safe almost instantly by a simple interlocking guard. When the microwave door is open the magnetron stops. Another example very close to home is the microwave oven. The door is the guard that protects the user from the hazards associated with the operation of the magnetron and the microwaves produced inside the microwave oven.
- You cannot start the microwave with the door open.
- Also, the magnetron in the oven stops as soon as the door is opened, rendering the radiation hazard safe without the necessity of guard locking.
- Just be careful of the hot food!! It all goes back to the risk assessment where the hazards associated with the operation of the specific machine are identified and addressed to “achieve safety in the design of machinery.” As the CE blogs and this one show, guard selection takes some serious consideration and design, and it is not to be taken lightly.
Fortunately, we have consensus standards from both ISO and American National Standards Institute (ANSI) to help guide the designer through the process. In the next blog I will provide a brief glossary of standards that can guide machine designers in creating safe, effective, and user-friendly guards for both consumer and industrial machinery.
- Chad Jones, PE, CMSE, CFEI has a Bachelor of Science in Mechanical Engineering from Clemson University.
- Chad has over 20 years of engineering experience including mechanical, process, and manufacturing engineering.
- This work has included equipment design, machine safeguarding, cost estimating and safety compliance.
Chad also has over 10 years of commercial, industrial, and residential HVAC and plumbing design experience. Chad is a Certified Fire and Explosion Investigator and IFSAC certified Firefighter II in Greenwood County, South Carolina.
How do you identify different guards?
Telling the regiments apart – Two officers and a Warrant Officer class I of the Irish Guards – in this image the blue plume can be seen on the right hand side of the bearskin, the tunic buttons are grouped in fours, and the shamrock badge is on the collar. The Officer on the far side has a parachute badge indicating he’s trained to deploy as a parachutist.
- The colour of the plume, and which side of the bearskin it is worn on
- The spacing of the tunic buttons
- The badge worn on the collar
- The badge worn on the shoulder
| Regiment | Plume | Plume colour | Button spacing | Collar badge | Shoulder badge |
|---|---|---|---|---|---|
| Grenadier Guards | Left | White | Singly | Grenade | Royal Cypher |
| Coldstream Guards | Right | Red | Pairs | Garter Star | Rose |
| Scots Guards | — | — | Threes | Thistle | Thistle Star |
| Irish Guards | Right | Blue | Fours | Shamrock | St Patrick Star |
| Welsh Guards | Left |
|
Fives | Leek | Leek |
The rank insignia for officers are also differentiated by what specific stars are used. Left to right: Rank slides used by Grenadier, Coldstream, and Welsh Guards. Rank slides used by Scots Guards. Rank slides used by Irish Guards. Standard rank slides used by other army officers.
How many guards units are there?
The five Regiments of Foot Guards are the Grenadier Guards, the Coldstream Guards, the Scots Guards, the Irish Guards and the Welsh Guards.
What are the 4 Guards?
From Wikipedia, the free encyclopedia
| 4th Guards Army | |
|---|---|
| Active | 1943–1947 |
| Country | Soviet Union |
| Branch | Red Army / Soviet Army |
| Type | Field army |
| Engagements | World War II
Battle of Kursk Battle of the Dnieper Dnieper-Carpathian Offensive Battle of the Korsun–Cherkassy Pocket Uman–Botoșani Offensive Second Jassy–Kishinev Offensive Budapest Offensive Vienna Offensive |
| Commanders | |
| Notable commanders | Grigory Kulik Georgiy Zakharov |
The 4th Guards Army was an elite Guards field army of the Soviet Union during World War II and the early postwar era.
What are the 3 Guards?
Postwar – The 3rd Guards Army briefly became part of the when it was formed on 10 June 1945. At that time, it included the with the,, and, the with the,, and, and the with the,, and, The same Stavka order that established the group ordered the disbandment of the army’s three rifle corps and all nine of its divisions, a process completed by July.
Who protects the Queen?
The King’s Life Guard are sentry postings at Horse Guards, staffed by a cavalry contingent. The King’s Guard (called the Queen’s Guard when the reigning monarch is female) are sentry postings at Buckingham Palace and St James’s Palace, organised by the British Army ‘s Household Division,
- The Household Division also mounts sentry postings at Horse Guards, known as the King’s Life Guard (called the Queen’s Life Guard when the monarch is female).
- An infantry contingent, typically one of the Household Division’s five regiments of foot guards, mounts the King’s Guard, while the King’s Life Guard is usually provided for by the Household Cavalry Mounted Regiment,
Since the 20th century, several other British Army units, Royal Air Force units, Royal Navy units, and military units from other Commonwealth countries have been invited to form the King’s Guard. In addition to the King’s Guard, the Household Division also provide for several other sentry postings including the Tower of London Guard and the Windsor Castle Guard,
What are the 4 guards?
From Wikipedia, the free encyclopedia
| 4th Guards Army | |
|---|---|
| Active | 1943–1947 |
| Country | Soviet Union |
| Branch | Red Army / Soviet Army |
| Type | Field army |
| Engagements | World War II
Battle of Kursk Battle of the Dnieper Dnieper-Carpathian Offensive Battle of the Korsun–Cherkassy Pocket Uman–Botoșani Offensive Second Jassy–Kishinev Offensive Budapest Offensive Vienna Offensive |
| Commanders | |
| Notable commanders | Grigory Kulik Georgiy Zakharov |
The 4th Guards Army was an elite Guards field army of the Soviet Union during World War II and the early postwar era.
What are the 3 guards?
Postwar – The 3rd Guards Army briefly became part of the when it was formed on 10 June 1945. At that time, it included the with the,, and, the with the,, and, and the with the,, and, The same Stavka order that established the group ordered the disbandment of the army’s three rifle corps and all nine of its divisions, a process completed by July.
What is the highest level of guards?
Understanding the Ranking System in the Security Field – In the security field, ranking systems differ depending on the company. Generally, however, ranks range from watchman at the lowest rank to commander or chief at the highest rank. Here are the rankings and their meanings. Security officers may also have differing titles.
What is the highest rank of guard?
Previous flag – This positional flag for the chief of the National Guard Bureau was used from 1998 to 2008. The dark blue represented the Army National Guard, the light blue represented the Air National Guard. The badge in the center is the branch insignia of the National Guard Bureau.